Mobile floor cleaning robot

ABSTRACT

A pad particularly adapted for surface cleaning. The pad includes an absorbent core having the ability to absorb and retain liquid material, and a liner layer in contact with and covering at least one side of the absorbent core. The liner layer has the ability to retain and wick liquid material through the liner layer. Cleaning apparatus containing such pads and methods of using such pads are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation-In-Part of U.S. applicationSer. No. 14/077,296 entitled “Autonomous Surface Cleaning Robot” filedNov. 12, 2013, now U.S. Pat. No. 9,427,127, and claims the benefit ofU.S. Provisional Patent Application Ser. No. 61/902,838 entitled“Cleaning Pad” filed Nov. 12, 2013, and U.S. Provisional PatentApplication Ser. No. 62/059,637 entitled, “Surface Cleaning Pad” filedOct. 3, 2014. Each of the aforementioned applications is assigned to anentity common hereto. Further, the entirety of each one of theaforementioned patent applications is incorporated herein by referencefor all purposes.

TECHNICAL FIELD

This disclosure relates to floor cleaning using a cleaning pad.

BACKGROUND

Tiled floors and countertops routinely need cleaning, some of whichentails scrubbing to remove dried in soils. Various cleaning implementscan be used for cleaning hard surfaces. Most implements include acleaning pad that may be removably attached to the implement. Thecleaning pads may be disposable or reusable. In some examples, thecleaning pads are designed to fit a specific implement or may bedesigned for more than one implement.

Traditionally, wet mops are used to remove dirt and other dirty smears(e.g., dirt, oil, food, sauces, coffee, coffee grounds) from the surfaceof a floor. A person usually dips the mop in a bucket of water and soapor a specialized floor cleaning solution and rubs the floor with themop. In some examples, the person may have to perform back and forthscrubbing movements to clean a specific dirt area. The person then dipsthe mop in the same bucket of water to clean the mop and continues toscrub the floor. Additionally, the person may need to kneel on the floorto clean the floor, which could be cumbersome and exhausting, especiallywhen the floor covers a large area.

Floor mops are used to scrub floors without the need for a person go ontheir knees. A pad attached to the mop or an autonomous robot can scruband remove solids from surfaces and prevents a user from bending over toclean the surface, which prevents a injuries to the user.

SUMMARY

A surface cleaning pad is described including an absorbent corecontaining fiber material which absorbs and retains liquid material, aliner layer (also herein throughout called a “wrap layer”) in contactwith and covering at least one side of the absorbent core, containingfiber material which retains and wicks liquid material through the linerlayer. In embodiments, the cleaning pad is disposable or washable andreusable.

Additional embodiments include the following elements or characteristicstaken in combination or sub-combination to provide the advantages ofabsorbing and retaining fluid and suspended debris for a compact mobilerobot weighing less than 2.25 kg. The following elements orcharacteristics taken in combination or sub-combination create a padthat wicks moisture and debris into the absorbent core without expandingand raising the front edge of the lightweight robot, which would impedethe movement pattern and cleaning efficacy of the robot because maximumdownward force, such as 1 pound of force, would no longer be applied tothe pad: the pad described above where the pad absorbs about 20milliliters of liquid material in about 10 seconds with about 0.9 poundsof pressure on the pad; the pad described above where the absorbent coreretains up to about 90% by volume of the liquid material absorbed; thepad described above where the liquid material is substantially evenlydistributed throughout the absorbent core; the pad described above wherethe core material absorbs up to about 7 to about 10 times its weight;the pad described above where the liner layer retains up to about 10% ofthe liquid material absorbed; the pad described above where theabsorbent core comprises cellulose fibers; the pad described above wherethe absorbent core comprises a mixture of cellulosic and polymer fibers;the pad described above where the absorbent core comprises non-wovencellulose pulp; the pad described above where the cellulose pulp ispolymer bonded; the pad described above where the polymer comprisespolyethylene and/or polypropylene; the pad described above where theabsorbent core additionally contains a surface layer comprising acryliclatex, for example, to eliminate Tinting; the pad described above wherethe pad does not substantially compress or expand when absorbing orretaining liquid, for example, when wet; the pad described above wherethe pad includes a backing layer attached to the pad and particularlyadapted to attach the pad to a cleaning apparatus; the pad describedabove where the backing layer comprises cardboard; the pad describedabove where the cardboard backing layer is between 0.1 and 0.05 inchthick (0.254 cm to 0.127 cm thick); the pad described above where thecardboard backing layer is 0.028 inch thick (0.07 cm thick); the paddescribed above where the pad is coated with a polymer; the paddescribed above where the polymer coating is about 0.010 to about 0.040inch thick (0.0254 cm to 0.1016 cm thick); the pad described above wherethe polymer is any polymer or wax material that can seal against liquidpenetration, such as water, for example (such as polyvinyl alcohol orpolyamine, for example); the pad described above where the cardboard isattached to the pad with an adhesive; the pad described above where theabsorbent core comprises first, second, and third airlaid layers, eachairlaid layer having a top surface and a bottom surface, the bottomsurface of the first airlaid layer disposed on the top surface of thesecond airlaid layer, the bottom surface of the second airlaid layerdisposed on the top surface of the third airlaid layer; the paddescribed above where the liner layer is wrapped around and covers atleast two sides of the absorbent core; the pad described above where theliner layer comprises a spunlace layer; the pad described above wherethe liner layer comprises a hydroentangled spunbond or spunlace layerhaving reduced thickness indentations therein on a floor facing surfaceand having a basis weight of 35-40 gsm (grams per square meter). When apad 100 is damp, not enough fluid is present to lubricate the interfacebetween the bottom surface of the pad and the floor surface. A fullywetted pad will ride on a layer of fluid while the pad is moving over afloor surface, but as the damp pad slowly absorbs fluid, the not fullywet, not fully lubricated, wrap layer will drag on the floor surface. Inimplementations, the spunbond or spunlace wrap layer is manufacturedwith hydrophilic fibers that minimize the surface area of the padexposed to air between the pad and the floor surface. A wet pad wouldstick to the hydrophilic floor surface if the indentations or needlepunches were not part of the wrap layer. Applying a surface texture tothe spunbond or spunlace of the wrap layer, such as a herringboneindentation patter or a square grid indentation pattern, breaks thesurface tension that would otherwise case a wet pad to stick to a wetfloor surface.

In implementations of the pad, the liner layer includes meltblownabrasive fibers adhered to the side of the liner layer not in contactwith the absorbent core; the pad described above where the meltblownfibers have a diameter of between about 0.1 μm and about 20 μm; the paddescribed above where the meltblown abrasive fibers cover between about44 percent and about 75 percent of the surface of the liner layer; Inimplementations of the pad, the meltblown abrasive fibers cover betweenabout 50% and about 60% of the surface of the liner layer. The meltblownlayer provides the pad with the advantages of breaking surface tensionthat might otherwise cause the wet wrap layer to stick to a wet floor.By adding texture and topography to a floor facing surface of the pad,the meltblown layer prevents the pad from sticking or encountering highdrag forces. The meltblown layer also provides the pad with surfacetexture for roughing up dirt and debris stuck or dried to a floorsurface and loosening dirt and debris for absorption by the airlaidinner core of the pad. In implementations of the pad the meltblownabrasive fibers and the liner layer have a collective thickness ofbetween about 0.5 mm (millimeter) and about 0.7 mm. In other words, themaximum overlapped thickness from the outer layer of the appliedmeltblown to the surface of the wrap layer is 0.7 mm. In implementationsof the pad, the wrap layer has a thickness of between about 0.5 mm andabout 0.7 mm. In implementations, the wrap layer has a WorldwideStrategic Partners (WSP) 10.1 (05) nonwoven materials water absorptiontest specification value of about 600%; the pad described above wherethe pad increases in thickness by less than 30% after liquid materialabsorption. In implementations, the pad additionally contains one ormore of a scent agent, cleaning agent, surfactant, foaming agent,glossing agent, chemical preservative, debris retention agent (such asDRAKESOL) and/or anti-bacterial agent. In implementations, the pad has athickness of between about 6.5 mm and about 8.5 mm. In implementations,the pad has a width of between about 68 millimeters and about 80millimeters and a length of between about 165 millimeters and about 212millimeters. In implementations, the liner layer has a width of betweenabout 163 millimeters and about 169 millimeters and a length betweenabout 205 millimeters and about 301 millimeters. In implementations, theabsorbent core comprises a first airlaid layer adhered to a secondairlaid layer and the second airlaid layer is adhered to a third airlaidlayer.

Fluid wicks between the three layers and is retained uniformlyvertically throughout the stack of airlaid layers without leaking backonto a floor surface beneath the cleaning pad while downward force isapplied to the pad. In implementations, the pad retains 90 percent offluid applied to a floor surface and under 1 pound of force, the paddoes not leak absorbed fluid back onto the floor surface. The surfacetension the top and bottom surfaces of each airlaid layer helps retainwicked fluid within each layer such that as the top layer fullysaturates, no fluid will leak down to the middle airlaid layer throughthe bottom surface 11 b of the top airlaid layer, and as the middleairlaid layer fully saturates, no fluid will leak down to the bottomlayer through the bottom surface of the middle (or second) layer.

In implementations, the pad soaks up 8-10 times its weight in fluid intoa relatively rigid matrix of airlaid layers that does not deform in anydimension when fully wet, and fluid absorption is achieved throughcapillary wicking, not by compress-release drawing because robot towhich the pad is attached exerts very light, low variability cycleweight, not a cycle of heavy human push down and draw back. Each ofairlaid layer slows down penetration of wicked fluid to the nextadjacent airlaid layer such that early cycles of fluid application donot lead to the pay quickly sopping up all the fluid that is applied tothe floor surface. The vertical stack of airlaid layers provides aresistance to puddling at the bottom of the airlaid core comprising thethree airlaid layers. Each of the of airlaid layers has its own puddleresisting bottom surface for preventing puddling of absorbed fluid allthe way down at the bottom of the bottom surface of the bottom (orthird) layer.

In implementations, the airlaid layers are of non-uniform hardness ordensity in the vertically direction such the outer top and bottomsurfaces are harder than the interior of each layer. In embodiments, asa characteristic of the manufacturing process, the airlaid layers are ofnon-uniform surface density such that the outer top and bottom surfacesare smoother and less absorptive than the interior of each layer. Byvarying the surface density at the outer surfaces of each of the airlaidlayer, the airlaid layers remain absorptive, wicking fluid into eachairlaid layer without leaking back through the bottom surfaces. Byincorporating three such airlaid layers into the absorptive core of thepad, the pad therefore has superior fluid retention properties over apad having a single core of thickness equivalent to the three layerstacked core. The three airlaid layers provide at least triple theamount of surface tension for

In implementations of the pad, the three airlaid layers are adhered toeach other by means of an adhesive material. In some implementations,the adhesive material is applied in at least two evenly spaced stripsalong the length of at least one side of an airlaid layer and covers notmore than 10% of the surface area of the at least one side. Inimplementations, of the pad the adhesive material is sprayed on thelength of at least one side of an airlaid layer and covers not more than10% of the surface area of the at least one side. In implementations ofthe pad, at least one airlaid layer comprises a cellulose based textilematerial. In some implementations, at least one airlaid layer, andpreferably all three airlaid layers, comprises wood pulp. In someimplementations, one or more of the airlaid layers comprisesbiocomponent polymers, cellulose, and latex and the polymer is presentin an amount up to about 15% by weight.

A method for constructing a cleaning pad is also described, includingdisposing a first airlaid layer on a second airlaid layer; disposing thesecond airlaid layer on a third airlaid layer; and wrapping a wrap layeraround the first, second, and third airlaid layers, the wrap layercomprising: a fiber composition; and a meltblown abrasive adhered to thefiber composition on an outer surface positioned to interface with afloor surface beneath the cleaning pad, the fiber composition being aspunlace or spunbond material.

Additional embodiments of the method for constructing a cleaning padinclude the following elements or characteristics taken in combinationor sub-combination to provide the advantages of scrubbing debris from afloor surface and absorbing and retaining fluid and suspended debriswhen the pad is attached to a compact mobile robot weighing less than2.25 kg without impeding the back and forth birdsfoot or viningscrubbing pattern and cleaning efficacy of the robot. The followingelements or characteristics taken in combination or sub-combinationcreate a pad that wicks moisture and debris into the absorbent corewithout expanding and raising the front edge of the lightweight robot,which would prevent the robot from applying maximum downward force tothe pad: the method further comprising adhering and randomly arrangingmeltblown abrasive fibers on the wrap layer; the method described abovewhere the meltblown abrasive fibers having a diameter of between about 8μm and about 20 μm; the method described above further comprisingarranging the meltblown abrasive and the wrap layer to have a collectivethickness of between about 0.5 mm and about 0.7 mm; the method describedabove further comprising arranging the meltblown abrasive on the wraplayer to provide a covered surface ratio between the meltblown abrasiveand the wrap layer of between about 44% and 57%; the pad described abovewhere the meltblown abrasive fibers cover between about 50% and about60% of the surface of the liner layer; the method described abovefurther comprising adhering the first airlaid layer to the secondairlaid layer and adhering the second airlaid layer to the third airlaidlayer; the method described above where the airlaid layer is a cellulosebased textile material; the method described above where the first,second, and third airlaid layers, the spunlace layer, and the meltblownabrasive are configured to increase in thickness by less than 30% afterfluid absorption; the method described above further comprisingconfiguring the airlaid layers and wrap layer to have a combined widthof between about 80 millimeters and about 68 millimeters and a combinedlength of between about 200 millimeters and about 212 millimeters; themethod described above further comprising configuring the airlaid layersand the wrap layer to have a combined thickness of between about 6.5millimeters and about 8.5 millimeters; the method described abovefurther comprising configuring the airlaid layers have a combinedairlaid width of between about 69 millimeters and about 75 millimetersand a combined airlaid length between about 165 millimeters and about171 millimeters.

A surface cleaning apparatus is also described having attached theretothe cleaning pad described above. Additional embodiments include wherethe surface cleaning apparatus is a mop or autonomous mobile robot; thesurface cleaning apparatus described above where the pad is releaseablyattached to the surface cleaning apparatus through a backing layerattached to the pad; the surface cleaning apparatus described abovewhere the backing layer comprises cardboard; and the surface cleaningapparatus described above where the surface cleaning apparatusadditionally contains a release mechanism to eject the releaseablyattached pad.

A method of cleaning a surface with the pad described above is alsodescribed, including applying a surface cleaning liquid to the surfaceto be cleaned and passing the surface cleaning pad over the surface. Thepad absorbs about 20 milliliters of liquid material in about 10 secondswith about 400 gram-force of pressure on the pad. In someimplementations, the absorbent core retains up to about 90% by volume ofthe liquid material absorbed. In some implementations, liquid materialabsorbed is substantially evenly distributed throughout the core. Insome implementations, the core material absorbs up to about 7 to about10 times its weight. In some implementations, the liner layer retains upto about 10% of the liquid material absorbed.

A mobile robot is also described. In implementations, the robot includesa robot body defining a forward drive direction, a drive supporting therobot body to maneuver the robot across a floor surface, and a cleaningassembly disposed on the robot body. The cleaning assembly includes apad holder configured to receive a cleaning pad having a center andlateral edges, and the pad holder comprises a release mechanismconfigured to eject the pad upon actuation of a release mechanism. Therobot further includes a fluid applicator configured to apply fluid tothe floor surface, wherein, and a controller circuit in communicationwith the drive and the cleaning assembly, the controller circuitcontrolling the drive and fluid applicator while executing a cleaningroutine. The cleaning routine includes applying fluid to a floor surfacearea substantially equal to a footprint area of the robot, and returningthe robot to the floor surface area in a movement pattern that moves thecenter and lateral edges of the cleaning pad separately through thefloor surface area to moisten the entire surface area of the cleaningpad with the applied fluid.

Additional implementations include the robot described above where thecleaning routine further comprises applying fluid to the floor surfaceat an initial volumetric flow rate to moisten the cleaning pad, theinitial volumetric flow rate being relatively higher than a subsequentvolumetric flow rate when the cleaning pad is moistened. In oneimplementation, the first volumetric flow rate is set by spraying about1 mL of fluid every 1.5 feet initially for a period of time such as 1-3minutes, and the second volumetric flow rate is set by spraying every 3feet, wherein each spray of fluid is less than 1 mL of volume. The fluidapplicator applies fluid to a floor surface area in front of thecleaning pad and in the forward drive direction of the mobile robot, andthe fluid is applied to a floor surface area previously occupied by thecleaning pad. In implementations, the previously occupied floor surfacearea is stored on a map accessible to the controller circuit. Inimplementations, fluid is applied to a floor surface area the robot hasbacked away from by a distance of at least one robot footprint lengthimmediately prior to applying fluid so that the fluid is only applied totraversable floor and not to a wall, piece of furniture, carpet or othernon-floor area that triggers a bump sensor (collision) switch orproximity sensor on the robot. In implementations, executing thecleaning routine further comprises moving the cleaning pad in abirdsfoot motion forward and backward along a center trajectory, forwardand backward along a trajectory to a left side of and heading away froma starting point along the center trajectory, and forward and backwardalong a trajectory to a right side of and heading away from a startingpoint along the center trajectory. The robot drive comprises right andleft drive wheels disposed on corresponding right and left portions ofthe robot body, and a center of gravity of the robot is positionedforward of the drive wheels, causing a majority of an overall weight ofthe robot to be positioned over the pad holder. Because the pad does notexpand during fluid absorption, the weight of the robot remainspositioned over the pad holder throughout the cleaning routine. Theoverall weight of the robot is distributed between the pad holder andthe drive wheels at a ratio of 3 to 1, and the overall weight of therobot without retaining any fluid is between about 1 kg and about 1.5 kgand with retaining fluid is between about 1.5 kg to 4.5 kg. Inimplementations, the robot body and the pad holder both definesubstantially rectangular foot prints. Additionally, in implementations,the robot further includes a vibration motor disposed on a top portionof the pad holder. In some implementations, the robot further includes atoggle button for actuating the pad holder release mechanism andejecting the pad. A backing layer on the pad engages with the padholder, and the pad holder comprises raised protrusions positioned foraligning to and engaging with one or more shaped slots cut out of thebacking layer along a peripheral edge of the backing layer. In someimplementations, the pad holder comprises raised protrusions positionedfor aligning to and engaging with one or more shaped slots cut out ofthe backing layer at a location other than along a peripheral edge.

A mobile floor cleaning robot is also described including a robot bodydefining a forward drive direction, a drive supporting the robot body tomaneuver the robot across a surface, the drive comprising right and leftdrive wheels disposed on corresponding right and left portions of therobot body. The robot includes a cleaning assembly disposed on the robotbody, the cleaning assembly having a pad holder disposed forward of thedrive wheels and having a top portion and a bottom portion, the bottomportion having a bottom surface arranged within between about 0.5 cm andabout 1.5 cm of the surface and configured to receive a cleaning pad.The bottom surface of the pad holder includes at least 40 percent of asurface area of a footprint of the robot, and the bottom surface havingone or more raised protrusions extending therefrom for engaging withmating slots on a pad assembly. In implementations, the robot includesan orbital oscillator having less than 1 cm of orbital range disposed onthe top portion of the pad holder. The pad holder is configured topermit more than 80 percent of the orbital range of the orbitaloscillator to be transmitted from the top of the received cleaning padto the bottom surface of the received cleaning pad. The one or moreprotrusions assist with aligning the pad to the pad holder and retainingthe pad securely in place during oscillation of the orbital oscillationwhile the robot moves in a back and forth scrubbing cleaning pattern. Inimplementations, the pad holder includes a release mechanism configuredto eject the pad from the bottom surface of the pad holder uponactuation of the release mechanism such that a user need not touch aused, dirty pad to dispose of it. Actuating the release mechanism whileholding the robot above a trash container ejects the pad from the padholder into the trash container therebeneath.

In some implementations, the orbital range of the orbital oscillator isless than 0.5 cm during at least part of a cleaning run. Additionally,the robot drives forward and backward while oscillating the cleaningpad. In implementations, the robot drives in a birdsfoot motion to movethe cleaning pad forward and backward along a center trajectory, forwardand backward along a trajectory to a left side of and heading away froma starting point along the center trajectory, and forward and backwardalong a trajectory to a right side of and heading away from a startingpoint along the center trajectory. The cleaning pad has a top surfaceattached to the bottom surface of the pad holder and the top of the padis substantially immobile relative to the oscillating pad holder. Inimplementations, the robot cleaning assembly further includes areservoir to hold a volume of fluid and a fluid applicator in fluidcommunication with the reservoir. The fluid applicator is configured toapply the fluid along the forward drive direction forward of the padholder. The cleaning pad is configured to absorb about 90 percent of thefluid volume held in the reservoir without leaking onto the floorsurface beneath the pad while receiving 1 pound of downward force. Thepad further includes a backing layer on the cleaning pad for engagingwith the pad holder and one or more raised protrusions on the bottom ofthe pad holder are positioned for aligning to and engaging with shapedslots cut out of the backing layer. The one or more protrusions assistwith aligning the pad to the pad holder and retaining the pad securelyin place during oscillation of the orbital oscillation while the robotmoves in a back and forth scrubbing cleaning pattern. Inimplementations, the pad holder includes a release mechanism configuredto eject the pad from the bottom surface of the pad holder uponactuation of the release mechanism such that a user need not touch aused, dirty pad to dispose of it. Actuating the release mechanism whileholding the robot above a trash container ejects the pad from the padholder into the trash container therebeneath.

A method of operating a mobile floor cleaning robot is also describedincluding driving in a forward drive direction defined by the robot afirst distance to a first location while moving a cleaning pad carriedby the robot along a floor surface supporting the robot, the cleaningpad having a center and lateral edges; driving in a reverse drivedirection, opposite the forward drive direction, a second distance to asecond location while moving the cleaning pad along the floor surface;from the second location, applying fluid to an area substantially equalto a footprint area of the robot on the floor surface in the forwarddrive direction forward of the cleaning pad but rearward of the firstlocation; and returning the robot to the area in a movement pattern thatmoves the center and lateral edges of the cleaning pad separatelythrough the area to moisten the cleaning pad with the applied fluid.

Additional embodiments include: the method described above furthercomprising driving in a left drive direction or a right drive directionwhile driving through the applied fluid in the alternating forward andreverse directions after spraying fluid on the floor surface; the methoddescribed above where fluid on the floor surface comprises sprayingfluid in multiple positions with respect to the forward drive direction;the method described above where the second distance is at least equalto a length of one footprint area of the robot; the method describedabove where the mobile floor cleaning robot comprises: a robot bodydefining the forward drive direction and having a bottom portion, and adrive system supporting the robot body and configured to maneuver therobot over the floor surface.

One aspect of the disclosure provides a mobile robot having a robotbody, a drive system, and a cleaning assembly. The cleaning assemblyincludes a pad holder, a fluid applicator and a controller. The drivesystem supports the robot body to maneuver the robot across a floorsurface. The cleaning assembly is disposed on the robot body andincludes a pad holder, a fluid applicator and a controller incommunication with the drive system and the cleaning system. The padholder is configured to receive a cleaning pad having a center andlateral edges. The pad holder includes a release mechanism configured toeject the pad upon actuation of a release mechanism. The fluidapplicator is configured to apply fluid to the floor surface. Thecontroller controls the drive system and fluid applicator whileexecuting a cleaning routine. The cleaning routine includes applyingfluid to an area substantially equal to a footprint area of the robot,and returning the robot to the area in a movement pattern that moves thecenter and lateral edges of the cleaning pad separately through the areato moisten the cleaning pad with the applied fluid.

Implementations of the disclosure may include one or more of thefollowing features. In some implementations, the cleaning routinefurther includes applying fluid to the surface at an initial volumetricflow rate to moisten the cleaning pad, the initial volumetric flow ratebeing relatively higher than a subsequent volumetric flow rate when thecleaning pad is moistened. In one implementation, the first volumetricflow rate is set by spraying about 1 mL of fluid every 1.5 feetinitially for a period of time such as 1-3 minutes, and the secondvolumetric flow rate is set by spraying every 3 feet, wherein each sprayof fluid is less than 1 mL of volume.

In some examples, the fluid applicator applies fluid to an area in frontof the cleaning pad and in the direction of travel of the mobile robot.In some examples, the fluid is applied to an area the cleaning pad hasoccupied previously. In some examples, the area the cleaning pad hasoccupied is recorded on a stored map that is accessible to thecontroller.

In some examples, the fluid applicator applies fluid to an area therobot has backed away from by a distance of at least one robot footprintlength immediately prior to applying fluid. Executing the cleaningroutine further comprises moving the cleaning pad in a birdsfoot motionforward and backward along a center trajectory, forward and backwardalong a trajectory to the left of and heading away from a starting pointalong the center trajectory, and forward and backward along a trajectoryto the right of and heading away from a starting point along the centertrajectory.

In some implementations, the drive system includes right and left drivewheels disposed on corresponding right and left portions of the robotbody. A center of gravity of the robot is positioned forward of thedrive wheels, causing a majority of an overall weight of the robot to bepositioned over the pad holder. The overall weight of the robot 20 maybe distributed between the pad holder and the drive wheels at a ratio of3 to 1. In some examples, the overall weight of the robot is betweenabout 2 lbs. and about 5 lbs.

In some examples, the robot body and the pad holder both definesubstantially rectangular foot prints. Additionally or alternatively,the bottom surface of the pad holder may have a width of between about60 millimeters and about 80 millimeters and a length of between about180 millimeters and about 215 millimeters.

In some implementations, the robot includes a toggle button foractuating the pad holder release mechanism and ejecting the pad. In someimplementations, the pad includes a backing layer for engaging with thepad holder and the pad holder comprises raised protrusions positionedfor aligning to and engaging with shaped slots cut out of the backinglayer.

One aspect of the disclosure provides a mobile floor cleaning robothaving a robot body, a drive, a cleaning assembly, a pad holder, and acontroller circuit. The robot body defines a forward drive direction.The drive supports the robot body to maneuver the robot across a floorsurface. The cleaning assembly is disposed on the robot body andincludes a pad holder, a reservoir, and a sprayer. The pad holder has abottom surface configured to receive a cleaning pad and arranged toengage the floor surface, and the bottom surface has one or more raisedprotrusions extending therefrom.

The one or more protrusions assist with aligning the pad to the padholder and retaining the pad securely in place during oscillation of theorbital oscillation while the robot moves in a back and forth scrubbingcleaning pattern. In implementations, the pad holder includes a releasemechanism configured to eject the pad from the bottom surface of the padholder upon actuation of the release mechanism such that a user need nottouch a used, dirty pad to dispose of it. Actuating the releasemechanism while holding the robot above a trash container ejects the padfrom the pad holder into the trash container therebeneath.

The reservoir is configured to hold a volume of fluid, and the sprayer,which is in fluid communication with the reservoir, is configured tospray the fluid along the forward drive direction forward of the padholder. The controller circuit communicates with both the drive systemand the cleaning system and executes a cleaning routine. The controllercircuit executes a cleaning routine that allows the robot to drive inthe forward drive direction a first distance to a first location andthen drive in a reverse drive direction, opposite the forward drivedirection, a second distance to a second location. The cleaning routineallows the robot to spray fluid on the floor surface from the secondlocation, in the forward drive direction forward of the pad holder butrearward of the first location. In this manner, the robot only appliesfluid to traversable floor and not to a wall, piece of furniture, carpetor other non-floor area that triggers a bump sensor (collision) switchor proximity sensor on the robot. After spraying fluid on the floorsurface, the cleaning routine allows the robot to drive in alternatingforward and reverse drive directions while smearing the cleaning padalong the floor surface.

Implementations of the disclosure may include one or more of thefollowing features. In some implementations, the drive includes rightand left drive wheels disposed on corresponding right and left portionsof the robot body. A center of gravity of the robot is positionedforward of the drive wheels, causing a majority of an overall weight ofthe robot to be positioned over the pad holder. The overall weight ofthe robot may be distributed between the pad holder and the drive wheelsat a ratio of 3 to 1. In some examples, the overall weight of the robotis between about 2 lbs. and about 5 lbs (about 1 to 2.25 kg). The drivemay include a drive body, which has forward and rearward portions, andright and left motors disposed on the drive body. The right and leftdrive wheels may be coupled to the corresponding right and left motors.The drive system may also include an arm that extends from the forwardportion of the drive body. The arm is pivotally attachable to the robotbody forward of the drive wheels to allow the drive wheels to movevertically with respect to the floor surface. The rearward portion ofthe drive body may define a slot sized to slidably receive a guideprotrusion extending from the robot body.

In some examples, the robot body and the pad holder both definesubstantially rectangular foot prints. Additionally or alternatively,the bottom surface of the pad holder may have a width of between about60 millimeters and about 80 millimeters and a length of between about180 millimeters and about 215 millimeters.

The reservoir may hold a fluid volume of about 200 milliliters.Additionally or alternatively, the robot may include a vibration motor,or orbital oscillator, disposed on the top portion of the pad holder.

In some implementations, the robot includes a toggle button foractuating the pad holder release mechanism and ejecting the pad. In someimplementations, the pad includes a backing layer for engaging with thepad holder and the pad holder comprises raised protrusions positionedfor aligning to and engaging with shaped slots cut out of the backinglayer.

Another aspect of the disclosure provides a mobile floor cleaning robotthat includes a robot body, a drive, and a cleaning assembly. The robotbody defines a forward drive direction. The drive system supports therobot body to maneuver the robot across a floor surface. The cleaningassembly is disposed on the robot body and includes a pad holder and anorbital oscillator. The pad holder is disposed forward of the drivewheels and has a top portion and a bottom portion. The bottom portionhas a bottom surface arranged within between about 0.5 cm and about 1.5cm of the floor surface and receives a cleaning pad. The bottom surfaceof the pad holder includes at least 40 percent of a surface area of afootprint of the robot and has one or more raised protrusions extendingtherefrom. The orbital oscillator is disposed on the top portion of thepad holder and has an orbital range less than 1 cm. The pad holder isconfigured to permit more than 80 percent of the orbital range of theorbital oscillator to be transmitted from the top of the held cleaningpad to the bottom surface of the held cleaning pad.

In some examples, the orbital range of the orbital oscillator is lessthan ½ cm during at least part of a cleaning run. Additionally oralternatively, the robot may move the cleaning pad forward or backwardwhile the cleaning pad is oscillating.

The one or more protrusions assist with aligning the pad to the padholder and retaining the pad securely in place during oscillation of theorbital oscillation while the robot moves in a back and forth scrubbingcleaning pattern. In implementations, the pad holder includes a releasemechanism configured to eject the pad from the bottom surface of the padholder upon actuation of the release mechanism such that a user need nottouch a used, dirty pad to dispose of it. Actuating the releasemechanism while holding the robot above a trash container ejects the padfrom the pad holder into the trash container therebeneath.

In some examples, the robot moves in a birdsfoot motion forward andbackward along a center trajectory, forward and backward along atrajectory to the left of and heading away from a starting point alongthe center trajectory, and forward and backward along a trajectory tothe right of and heading away from a starting point along the centertrajectory.

In some examples, the cleaning pad has a top surface attached to thebottom surface of the pad holder and the top of the pad is substantiallyimmobile relative to the oscillating pad holder.

In some examples, the pad holder has a release mechanism configured toeject the pad from the bottom surface of the pad holder upon actuationof a release mechanism. In some examples, robot includes a toggle buttonfor actuating the pad holder release mechanism and ejecting the pad. Insome examples, the pad includes a backing layer for engaging with thepad holder and the pad holder comprises raised protrusions positionedfor aligning to and engaging with shaped slots cut out of the backinglayer.

In some examples, the overall weight of the robot is distributed betweenthe pad holder and the drive wheels at a ratio of 3 to 1. The overallweight of the robot may be between about 2 lbs. and about 5 lbs (about 1to 2.25 kg).

In some examples, the robot body and the pad holder both definesubstantially rectangular foot prints. Additionally or alternatively,the bottom surface of the pad holder may have a width of between about60 millimeters and about 80 millimeters and a length of between about180 millimeters and about 215 millimeters.

The cleaning assembly may further include at least one post disposed onthe top portion of the pad holder sized for receipt by a correspondingaperture defined by the robot body. The at least one post may have across sectional diameter varying in size along its length. Additionallyor alternatively, the at least one post may include a vibrationdampening material.

In some implementations, the cleaning assembly further includes areservoir to hold a volume of fluid, and a sprayer in fluidcommunication with the reservoir. The sprayer is configured to spray thefluid along the forward drive direction forward of the pad holder. Thereservoir may hold a fluid volume of about 200 milliliters.

The drive may include a drive body, which has forward and rearwardportions, and right and left motors disposed on the drive body. Theright and left drive wheels are coupled to the corresponding right andleft motors. The drive may also include an arm that extends from theforward portion of the drive body. The arm is pivotally attachable tothe robot body forward of the drive wheels to allow the drive wheels tomove vertically with respect to the floor surface. The rearward portionof the drive body may define a slot sized to slidably receive a guideprotrusion that extends from the robot body. In one implementation, thecleaning pad disposed on the bottom surface of the pad holder bodyabsorbs about 90% of the fluid volume held in the reservoir. Thecleaning pad has a thickness of between about 6.5 millimeters and about8.5 millimeters, a width of between about 80 millimeters and about 68millimeters, and a length of between about 200 millimeters and about 212millimeters.

In some examples, a method includes driving a first distance in aforward drive direction defined by the robot to a first location, whilemoving a cleaning pad carried by the robot along a floor surfacesupporting the robot. The cleaning pad has a center area and lateralareas flanking the center area. The method further includes driving in areverse drive direction opposite the forward drive direction, a seconddistance to a second location while moving the cleaning pad along thefloor surface In this manner, the robot only applies fluid totraversable floor and not to a wall, piece of furniture, carpet or othernon-floor area that triggers a bump sensor (collision) switch orproximity sensor on the robot. The method also includes applying fluidto an area on the floor surface substantially equal to a footprint areaof the robot and forward of the cleaning pad but rearward of the firstlocation. The method further includes returning the robot to the area ofapplied fluid in a movement pattern that moves the center and lateralportions of the cleaning pad separately through the area to moisten thecleaning pad with the applied fluid.

In some examples, the method includes driving in a left drive directionor a right drive direction while driving in the alternating forward andreverse directions after spraying fluid on the floor surface. Applyingfluid on the floor surface may include spraying fluid in multipledirections with respect to the forward drive direction. In someexamples, the second distance is at least equal to the length of afootprint area of the robot.

In still yet another aspect of the disclosure, a method of operating amobile floor cleaning robot includes driving a first distance in aforward drive direction defined by the robot to a first location whilesmearing a cleaning pad carried by the robot along a floor surfacesupporting the robot. The method includes driving in a reverse drivedirection, opposite the forward drive direction, a second distance to asecond location while smearing the cleaning pad along the floor surface.The method also includes spraying fluid on the floor surface in theforward drive direction forward of the cleaning pad but rearward of thefirst location. The method also includes driving in an alternatingforward and reverse drive directions while smearing the cleaning padalong the floor surface after spraying fluid on the floor surface.

In some implementations, the method includes spraying fluid on the floorsurface while driving in the reverse direction or after having driven inthe reverse drive direction the second distance. In implementations, thehe method includes driving in a left drive direction or a right drivedirection while driving in the alternating forward and reversedirections after spraying fluid on the floor surface. Spraying fluid onthe floor surface may include spraying fluid in multiple directions withrespect to the forward drive direction. In some implementations, thesecond distance is greater than or equal to the first distance.

The mobile floor cleaning robot may include a robot body, a drive, a padholder, a reservoir, and a sprayer. The robot body defines the forwarddrive direction and has a bottom portion. The drive system supports therobot body and maneuvers the robot over the floor surface. The padholder is disposed on the bottom portion of the robot body and holds thecleaning pad. The pad holder has a release mechanism configured to ejectthe pad upon actuation, and the pad further comprising a backing layerfor engaging with the pad holder. The pad holder has a bottom surfacehaving raised protrusions extending therefrom and the raised protrusionsare sized, shaped and positioned to align to and engage with slots cutout of the backing layer.

The reservoir is housed by the robot body and holds a fluid (e.g., 200ml). The sprayer, which is also housed by the robot body, is in fluidcommunication with the reservoir and sprays the fluid in the forwarddrive direction forward of the cleaning pad. The cleaning pad disposedon the bottom portion of the pad holder may absorb about 90% of thefluid contained in the reservoir. In some examples, the cleaning pad hasa width of between about 80 millimeters and about 68 millimeters and alength of between about 200 millimeters and about 212 millimeters. Thecleaning pad may have a thickness of between about 6.5 millimeters andabout 8.5 millimeters. The details of one or more implementations of thedisclosure are set forth in the accompanying drawings and thedescription below.

In some implementations, the fluid applicator is a sprayer that includesat least two nozzles each distributing the fluid evenly across the floorsurface in two strips of applied fluid. The two nozzles are eachconfigured to spray the fluid at an angle and distance different thananother nozzle. In some implementations, the two nozzles are verticallystacked in a recess in the fluid applicator and angled from horizontaland spaced apart from one another such that one nozzle sprays relativelylonger lengths of fluid forward and downward to cover an area in frontof the robot with a forward supply of applied fluid 173 a, and the othernozzle sprays relatively shorter lengths fluid forward and downward toleave a rearward supply of applied fluid on an area in front of butcloser to the robot than the area of applied fluid dispensed by the topnozzle.

In implementations, the nozzle or nozzles dispense fluid in an areapattern that extends one robot width and at least one robot length indimension. In some implementations, the top nozzle and bottom nozzleapply fluid in two distinct spaced apart strips of applied fluid that donot extend to the full width of the robot such that the pad passesthrough the outer edges of the strips of applied fluid in forward andbackward angled scrubbing motions as described herein. In embodiments,the strips of applied fluid cover a width of 75-95% of the robot widthand a combined length of the robot length. In implementations, thestrips of applied fluid may be substantially rectangular shaped orellipse shaped. In implementations, the nozzles complete each spraycycle by sucking in a small volume of fluid at the opening of the nozzleso that no fluid leaks from the nozzle following each instance ofspraying.

In some implementations, the pad includes a cardboard backing layeradhered to the top surface of the pad. The cardboard backing layerprotrudes beyond the longitudinal edges of the pad and the protrudinglongitudinal edges of the cardboard backing layer attach to the padholder of the robot. In one embodiment, the cardboard backing layer isbetween 0.02 inch and 0.03 inch thick (0.05 cm and 0.762 cm thick),between 68 and 72 mm wide and between 90-94 mm long. In one embodiment,the cardboard backing layer 85 is 0.026 inch thick, 70 mm wide and 92 mmlong. In one embodiment, the cardboard backing layer is coated on bothsides with a water resistant coating, such as wax or polymer or acombination of water resistant materials, such as wax/polyvinylalcohol/polyamine, and the cardboard backing layer does not disintegratewhen wetted.

In implementations, the pad is a disposable pad. In other examples, thepad is a reusable microfiber cloth pad having the same absorptivecharacteristics as those described herein with regard to embodiments. Inexamples having a washable, reusable microfiber cloth, the top surfaceof the cloth includes a secured stiff backing layer shaped andpositioned like the cardboard backing layer described with regard toembodiments. The stiff backing layer is made of heat resistant, washablematerial that withstands being machine dried without melting ordegrading the backing. The stiff backing layer is dimensioned and hascutouts as described herein for interchangeable use with the embodimentof the pad holder described with regard to embodiments herein.

In other examples, the pad is a disposable dry cloth and comprises asingle layer of needle punched spunbond or spunlace material havingexposed fibers for entrapping hair. The dry pad further comprises achemical treatment that adds a tackiness characteristic to the pad forretaining dirt and debris. In one embodiment, the chemical treatment isa material such as that marketed under the trade name DRAKESOL.

In some examples, the pad is secured to an autonomous robot through apad holder attached to the robot. A pad release mechanism adjusts to anup or pad-secure position. The pad release mechanism includes aretainer, or lip, that holds the pad securely in place by graspingprotruding longitudinal edges of a cardboard backing layer secured tothe top of the pad. In examples, the tip or end of the pad releasemechanism includes a moveable retention clip and an eject protrusionthat slides up through a slot or opening in the pad holder, and ispushed through the slot into a down position to release the secured padby pushing down on the attached cardboard backing layer.

Other aspects, features, and advantages will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is an exploded view of an exemplary cleaning pad.

FIG. 1B is an exploded view of the wrap layer of the exemplary cleaningpad of FIG. 1.

FIG. 1C is a section view of an exemplary cleaning pad.

FIG. 1D is a section view of an exemplary cleaning pad where the airlaidlayers include superabsorbent polymers.

FIG. 2A is a schematic view of an exemplary arrangement of operationsfor a spunlace process.

FIG. 2B is a perspective view of the hydroentaglement process for makingthe spunlace layer used in the exemplary cleaning pad.

FIG. 3 is a perspective view of a device for making the abrasivemeltblown layer used in the exemplary cleaning pad.

FIG. 4 is a perspective view of an autonomous mobile robot for cleaningusing the exemplary cleaning pad.

FIG. 5 is a perspective view of a mop using the exemplary cleaning pad.

FIG. 6 is a bottom view of an exemplary cleaning pad.

FIG. 7 is a schematic view of an exemplary arrangement of operations forconstructing a cleaning pad.

FIG. 8A is a perspective view of an exemplary cleaning pad.

FIG. 8B is an exploded perspective view of the exemplary cleaning pad ofFIG. 8A.

FIG. 8C is a top view of an exemplary cleaning pad.

FIG. 8D is a bottom view of an exemplary attachment mechanism for thepad as described herein.

FIG. 8E is a side view of an exemplary attachment mechanism for a pad asdescribed herein in a secure position.

FIG. 8F is a top view of an exemplary attachment holder for the pad asdescribed herein.

FIG. 8G is a cut away side view of an exemplary attachment mechanism forthe pad as described herein in a release position.

FIGS. 9A-9C are top views of an exemplary autonomous mobile robot as itsprays a floor surface with a fluid.

FIG. 9D is a top view of an exemplary autonomous mobile robot as itscrubs a floor surface.

FIG. 9E is a bottom view of an exemplary cleaning pad.

FIG. 9F is a top view of an exemplary autonomous mobile robot as itscrubs a floor surface.

FIG. 9G is a top view of an exemplary autonomous mobile robot as itscrubs a floor surface.

FIG. 10 is a schematic view of the robot controller of the exemplaryautonomous mobile robot of FIG. 4.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIGS. 1A, 1B and 1C, in some implementations, a disposablecleaning pad 100 includes a plurality of absorbent airlaid layers 101,102, 103 stacked, optionally bonded to one another, and enwrapped by anouter non-woven layer 105 which can have an abrasive meltblown elements106 disposed thereon. In some examples, the cleaning pad 100 includesone or more airlaid layers 101, 102, 103. As shown, the cleaning pad 100includes first, second and third airlaid layers 101, 102, 103, butadditional airlaid layers are possible as well. The number of airlaidlayers 101, 102, 103 may depend on the amount of cleaning fluid 172 thecleaning pad 100 is required to absorb. Each airlaid layer 101, 102, 103has a top surface 101 a, 102 a, 103 a and a bottom surface 101 b, 102 b,103 b. The bottom surface 101 b of the first (or top) airlaid layer 101is disposed on the top surface 102 a of the second airlaid layer 102,and the bottom surface 102 b of the second airlaid layer 102 is disposedon the top surface 103 a of the third (or bottom) airlaid layer 103.Fluid wicks between the three layers and is retained uniformlyvertically throughout the stack of airlaid layers without leaking backonto a floor surface beneath the cleaning pad 100 while downward forceis applied to the pad 100. In implementations, the pad 100 retains 90percent of fluid applied to a floor surface 10 and under 1 pound offorce, the pad 100 does not leak absorbed fluid back onto the floorsurface 10. The surface tension the top and bottom surfaces of eachairlaid layer helps retain wicked fluid within each layer such that asthe top layer 101 fully saturates, no fluid will leak down to the middleairlaid layer 102 through the bottom surface 101 b of the top airlaidlayer 101, and as the middle airlaid layer 102 fully saturates, no fluidwill leak down to the bottom layer through the bottom surface 102 b ofthe middle (or second) layer 102.

In implementations, the pad 100 soaks up 8-10 times its weight into arelatively rigid matrix of airlaid layers 101, 102, 103, and fluidabsorption is achieved through capillary wicking, not bycompress-release drawing because robot 400 to which the pad is attachedexerts very light, low variability cycle weight, not a cycle of heavyhuman push down and draw back. Each of airlaid layer 101, 102, 103 slowsdown penetration of wicked fluid to the next adjacent airlaid layer 101,102, 103, such that early cycles of fluid application do not lead to thepay quickly sopping up all the fluid that is applied to the floorsurface. The vertical stack of airlaid layers 101, 102, 103 provides aresistance to puddling at the bottom of the airlaid core comprising thethree airlaid layers 101, 102, 103. Each of the of airlaid layers 101,102, 103 has its own puddle resisting bottom surface 101 b, 102 b, 103 bfor preventing puddling of absorbed fluid all the way down at the bottomof the bottom surface 103 b of the bottom (or third) layer 103 b.

In embodiments, the airlaid layers 101, 102, 103 are of non-uniformhardness or density in the vertically direction such the outer top andbottom surfaces are harder than the interior of each layer. Inembodiments, the airlaid layers 101, 102, 103 are of non-uniform surfacedensity such that the outer top and bottom surfaces are smoother andless absorptive than the interior of each layer. By varying the surfacedensity at the outer surfaces 101 b, 102 b, 103 b of each of the airlaidlayer 101, 102, 103, the airlaid layers 101, 102, 103 remain absorptive,wicking fluid into each airlaid layer without leaking back through thebottom surfaces 101 b, 102 b, 103 b. By incorporating three such airlaidlayers 101, 102, 103 into the absorptive core of the pad 100, the pad100 therefore has superior fluid retention properties over a pad havinga single core of thickness equivalent to the three layer stacked core.The three airlaid layers 101, 102, 103 provide at least triple theamount of surface tension for retaining wicked fluid in the absorptivecores of each of the airlaid layers 101, 102, 103.

A wrap layer 104 wraps around the airlaid layers 101, 102, 103 andprevents the airlaid layers 101, 102, 103 from being exposed. The wraplayer 104 includes a wrap layer 105 (e.g., a spunlace layer) and anabrasive layer 106. The wrap layer 105 is wrapped around the first,second, and third airlaid layers 101, 102, 103. The wrap layer 105 has atop surface 105 a and a bottom surface 105 b. The top surface 105 b ofthe wrap layer 105 covers the airlaid layers 101, 102, 103. The wraplayer 105 may be a flexible material having natural or artificial fibers(e.g., spunlace or spunbond). The abrasive layer 106 is disposed on thebottom side 105 b of the wrap layer 105. Fluid applied to a floor 10beneath the cleaning pad 100 transfers through the wrap layer 105 andinto the airlaid layers 101, 102, 103. The wrap layer 105 wrapped aroundthe airlaid layers 101, 102, 103 is a transfer layer that preventsexposure of raw absorbent material in the airlaid layers. If the wraplayer 105 were too absorbent, the pad 100 would be suctioned onto afloor 10 and difficult to move. A robot, for example, may be unable toovercome the suction force while trying to move the cleaning pad 100across the floor surface 10. Additionally, the wrap layer 105 picks updirt and debris loosened by the abrasion outer layer 106 and may leave athin sheen of a cleaning fluid 172 on the surface 10 that air drieswithout leaving streak marks on the floor 10. The thin sheen of cleaningsolution is between 1.5 and 3.5 ml/square meter and dries in a durationno longer than three minutes, and preferably dries within between about2 minutes and 3 minutes.

The disposable cleaning pad 100 relies on capillary action (also knownas wicking) to absorb fluid on a floor surface 10. Capillary actionoccurs when a liquid is able to flow in narrow spaces without externalforces, such as gravity. Capillary action allows a fluid to move withinspaces of a porous material due to forces of adhesion, cohesion, andsurface tension. Adhesion of the fluid to the walls of a vessel willcause an upward force on the liquid edges and result in meniscus, whichturns upwards. The surface tension acts to hold the surface intact.Capillary action occurs when the adhesion to the walls is stronger thanthe cohesive forces between the fluid molecules.

In some examples, the airlaid layers 101, 102, 103 are a textile-likematerial made from fluff pulp, which is a type of wood pulp/chemicalpulp made from long fiber softwoods. Chemical pulp is created byapplying heat to a combination of wood chips and chemical materials in alarge container to break down the lignin (organic substance that bindsthe cells in the wood). The textile-like material that is made fromfluff pulp may be very bulky, porous, soft, and has good waterabsorption properties. The textile-like material does not scratch thefloor surface, maintains its strength even when it is wet, and may bewashed and reused.

Referring to FIG. 1D, in some implementations, the airlaid layers 101,102, 103 include an absorbent layer of a mixture of air-laid paper andsuperabsorbent polymers 108 (e.g., sodium polyacrylate) for wetness.Polymers include plastic and rubber materials, which are mainly organiccompounds that are chemically based on carbon, hydrogen, and othernonmetallic elements. Polymers generally have larger molecularstructures, which typically have low densities and may be extremelyflexible. Superabsorbent polymers 108 (also known as slush powder)absorb and retain large amounts of a fluid in comparison to their ownmass. The ability of the superabsorbent polymers 108 to absorb waterdepends on the ionic concentration of the aqueous solution. Asuperabsorbent polymer 108 may absorb up to 500 times its weight indeionized and distilled water (30-60 times its volume) and may become99.9% liquid. The absorbency of the superabsorbent polymers 108 dropssignificantly to about 50 times its weight when put into a 0.9% salinesolution. The valence cations in the saline solution prevent thesuperabsorbent polymer 108 from bonding with the water molecules. Thesuperabsorbent polymers 108 may expand causing the cleaning pad 100 toexpand as well. Various implements 400, 500 may use the cleaning pad100, and, in some examples, the implements 400, 500 may not support acleaning pad 100 that may expand. For example, expansion of the pad 100may disturb the physics of a compact, lightweight robot 400, causing thecompact robot 400 to tilt upward and apply less force to the pad 100 fordebris removal from the floor 10. Therefore, less superabsorbentpolymers 108 may be used to meet a cleaning pad absorbency requirement.In one embodiment, the pad 100 may contain pockets in a middle sectionalong the pad length that allow superabsorbent polymers to expand intothose pockets and allow the pad to maintain a constant thickness as thesuperabsorbent polymers expand.

In some implementations, the airlaid layers 101, 102, 103 include acellulose pulp nonwoven material that is through air bonded with abicomponent fiber. In some examples, fibers of wood pulp cellulose arethermally bonded with bicomponent polyethylene, and/or polypropylene,which has a low melting point. This mixture forms a solid absorbent corethat holds its formed shape and that evenly distributes absorbed fluid,preventing cleaning fluid from pooling at the lowest point in the layerand preventing additional fluid accumulation. The airlaid layers 101,102, 103 may be manufactured from a bleached wood pulp that looks like athick layer of cardboard. The pulp enters a hammer mill having blades ona rotor that strikes the thick layer of pulp and devibrates it intoindividual fibers. The individual fibers enter a distributor having ascreen rotor that looks like a flour sifter. The fibers are formed intoa sheet on another screen having an applied vacuum underneath, at whichstage the sheet is blended with a sheet of bicomponent fiber. Blown hotair melts the bicomponent to bond with the airlaid.

The airlaid layers are situated so as to distribute the absorbed liquidsubstantially uniformly throughout the core, without puddling of liquidanywhere in the core layers (expand?). The mobile robot 400 sprays fluid172 in front of the robot uniformly and the pad 100 picks up the appliedsolution 173 a, 173 b in an even distribution along its length whentraveling forward. In one embodiment, the airlayed layers 101, 102, 103are bonded with spray adhesive applied evenly over the surface of theairlaid layer 101, 102, 103. In one embodiment, the adhesive ispolyolefin and is applied in a thin, uniform manner to get reliableadhesion without creating ridges and stiff areas. The spray adhesivealso creates a uniformly bonded surface interface, allows fluid to wickinto the airlaid layers 101, 102, 103 without a large mechanical barrier(for example, stitches, or relatively large impermeable glue patches orridges) and this uniformly bonded surface interface between airlaidlayers 101, 102, 103 prevents puddling between the layers 101, 102, 103.

A very small amount of acrylic latex bonding agent may be sprayedsparingly on both the surfaces to bind the external layers and tominimize sloughing and help reduce linting. Linting is a condition thatoccurs when fine ravelings of cotton, linen, or fiber are apparent on anobject or fabric. The airlaid layers 101, 102, 103 may include 15% ofbiocomponent polymers, 85% cellulose, and latex at the top to eliminatelinting.

The wrap layer 105 may be of any material that is thin and absorbsfluid. In addition, the wrap layer 105 may be smooth to preventscratching the floor surface 10. In some implementations, the cleaningpad 100 may include one or more of the following cleaning agentconstituents butoxypropanol, alkyl polyglycoside, dialkyl dimethylammonium chloride, polyoxyethylene castor oil, linear alkylbenzenesulfonate, glycolic acid—which for example serve as surfactants, and toattack scale and mineral deposits, among other things; and includingscent, antibacterial or antifungal preservatives.

In some examples, the wrap layer 105 is a spunlace nonwoven material.Spunlace may also be known as hydroentangling, water entangling, jetentangling or hydraulic needling. Spunlace is a process of entangling aweb of loose fibers typically formed by a card on a porous belt ormoving perforated or patterned screen to form a sheet structure bysubjecting the fibers to multiple passes of fine high-pressure waterjets. The hydroentangling process enables formation of specialty fabricsby adding fibrous materials, such as tissue paper, airlaid, spunlace andspunbond nonwovens to composite non-woven webs. These materials offerperformance advantages needed for many wipe applications due to theirimproved performance or cost structure.

Referring to FIGS. 2A and 2B, the spunlace process 200 includes aprecursor web forming process 202 a. The precursor web is usually madeof staple textile-like fibers. These webs can be single fiber webs ormade of many different fiber blends. The typical four fibers of choiceare polyester, viscose, polypropylene and cotton. Variants of each ofthese fibers may also be used, such as organic cotton, as well asLyocell material, and Tencel rayon. PLA (polylactic acid) fibers whichare biodegradable can also be used.

The precursor web forming process 202 a may include forming airlaidcards, which may be used to provide a more isotropic web as a result ofhigher transversal orientation of the fibers. Carding is a method ofmaking thin webs of parallelized fibers. Higher bulk may also beobtained by using this type of carding system. Once the web of staplefibers is formed, a second layer of fibers may be placed on top of thisbase by air forming cellulose fibers, or by “laminating” a pre-formednonwoven web, such as tissue, spunlace or spunbond. In some examples,spunbond isisnonwoven material is combined is combined with airlaidlayers and thus the resulting fabric eliminates the carding step ofhydroentangling continuous fibers with cellulose pulp fibers. Thisfibrous composition then goes under a fiber entangling process 204constituted of rows of high-pressure water jets 210 that duplicate theconventional mechanical needling process and intertwine the fibersindividually, so that they become entangled forming a web 212.

The spunlace process 200 includes applying a fiber entangling process204 to the fibrous composition. The fiber entangling process 204includes jetting water from rows of high-pressure water jets 210 toduplicate the conventional mechanical needling process and intertwinethe fibers individually so that they become entangled, forming a web212. The web 212 (after going through the web forming and cardingprocess 202) is placed on a conveyor belt 214 rotated by two or morepulleys 216. During and/or after each water injection process the web212 goes through drums with suction 218 that suck the water out of thefiber and allow the fiber to keep moving to the next high-pressure waterjets 210.

The consolidated nonwoven substrate 215 is subsequently dried throughair-dryers in an air dryer process 206 and then wound in a windingprocess 208.

The wrap layer 105 can be printed on as well as thermally embossed.Embossing and debosing are processes for creating raised or recesseddesigns in fabric or other material. A relatively lower melt fiber, suchas polypropylene, may be used to achieve better thermal embossing. Thecoefficient of friction of the wrap layer 105 varies based on surfacetype and wetness. In on embodiment, a dry pad 100 moving on glass has acoefficient of friction of about 0.4 to about 0.5, and wet on tiles hasa coefficient of friction of about 0.25 to about 0.4. The wrap layer 105may include hydroembossing, which imparts three dimensional images onthe fabric. Hydroembossing is generally less expensive than thermalbonding. In one example, the wrap layer 105 is embossed with aherringbone pattern. The wrap layer 105 wrapped around a series ofairlaid layers 101, 102, 103 enables the formation of an absorbent corethat locks in absorbed fluid. The layering of airlaid core layers 101,102, 103 enables capillary action and retention throughout the combinedcore and within each individual layer 101, 102, 103. Furthermore, theairlaid layers 101, 102, 103 making up the core of the pad retain theirshape while distributing fluid evenly throughout each fluid retentionlayer and preventing pooling that would prohibit additional absorption.

The abrasion meltblown layer 106 includes meltblown fibers 107, whichare fibers formed by extruding a molten thermoplastic material through aplurality of fine, usually circular, die capillaries as molten threadsor filaments into converging high velocity gas streams that cut thefilaments of molten thermoplastic material to reduce their diameters.Thus, the meltblown fibers 107 are carried by the high velocity gasstream and placed on a surface that collects the fibers, thereforeforming a web of randomly distributed meltblown fibers 107.

In some examples, the abrasion meltblown layer 106 is a layer ofmeltblown fibers 107 that provide a rough surface. The meltblown fibers107 are formed by a meltblown process 300 (see FIG. 3) at highthroughput, which creates spittle, or hair like fibers, that are formedby a polymer drooled from the die orifices due to temperature and otherconditions in which it is run. The abrasive layer 106 is formed on topof the wrap layer 105 (e.g., another meltblown layer, a spunbond layer,or a spunlace layer). The wrap layer 105 may be a herring bonehydroembossed nonwoven material, which is made of a ratio of viscose(rayon) fibers blended with polyester fibers. In some examples, theabrasion meltblown layer 106 has a basis weight (also known as grammage)equal to 55 g/m² (grams per square meter). The wrap layer 105 may have abasis weight of between about 30 gsm (grams per square meter) and about65 gsm. In other examples, the wrap layer may have a basis weight ofbetween about 35-40 gsm. Basis weight is a measurement used in both thefabric and paper industries to measure the mass of the product per unitof area. In an embodiment, the wrap layer 105 is a hydroentangledspunbond or spunlace material formed with indentations (not show)therein that allow fluid and suspended dirt to pass more directlythrough to the airlaid layers 101, 102, 103 and reduce the amount ofcohesive suction between the wrap layer 105 and the floor surface 10when the pad 100 is wet. In one embodiment, the indentations are in aherringbone pattern. In another embodiment, the indentations form a gridof squares sized and spaced to be between 0.50 and 1.0 mm square andspaced apart in a grid formation by a length of 2.0-2.5 mm. In oneembodiment, the indentations are sized and spaced to be 0.75 mm squareand spaced apart in a grid formation by a length of 2.25 mm. In anotherembodiment, the wrap layer 105 is a spunbond or spunlace material havingneedle-punched holes therein for improving the wicking ability of thewrap layer 105 and decreasing the cohesion between the wet wrap layer105 and the floor surface 10. The herringbone, square and needle punchedindentations prevent a negative pressure from generating at the outsideof the wrap layer as fluid evaporates and/or wicks from the back of theliner. Without free movement inside the wrap layer 105 or some textureon the wrap layer 105, fluid applied to the floor surface 10 cannotreplace the wicked fluid, and that causes suction between the pad 100and the floor. Combining a low density spunbond or spunlace material of35-40 gsm with a surface texture in the form of hydroembossedindentations, surface textures and patterns (such as herringbone), orneedle punched indentations or holes prevents suction between the padand the floor. The meltblown layer 105 further assists with preventingthis suction force.

Additionally, when a pad 100 is damp, not enough fluid is present tolubricate the interface between the bottom surface of the pad and thefloor surface 10. A fully wetted pad 100 will ride on a layer of fluidwhile the robot 400 is moving, but as the damp pad 100 slowly absorbsfluid, the not fully wet, not fully lubricated, wrap layer 106 will dragon the floor surface 10. In implementations, the spunbond or spunlacewrap layer 105 is manufactured with hydrophilic fibers that minimize thesurface area of the pad 100 exposed to air between the pad 100 and thefloor surface 10. A wet pad 100 would stick to the hydrophilic floorsurface 10 if the indentations or needle punches were not part of thewrap layer 100. Applying a surface texture to the spunbond or spunlaceof the wrap layer 105 breaks the surface tension that would otherwisecase a wet pad 100 to stick to a wet floor surface 10.

The weight of the abrasion meltblown layer 106 is such that the abrasionmeltblown layer 106 acts as an absorbing layer and allows for fluid tobe absorbed through the meltblown layer 106 and be retained by theairlaid layer 101, 102, 103. In some examples, the meltblown layer 106covers about 60 to about 70% of the surface area of the spunlace wraplayer 105 and in other examples, the meltblown layer 106 covers about50-60% of the surface area of a spunbond or spunlace wrap layer 105.

The meltblown fibers 107 may have different arrangements andconfigurations on the spunlace wrap layer 105. In some examples, themeltblown fibers 107 are randomly arranged on the wrap layer 105. Themeltblown fibers 107 may be arranged in one or more sections 109 a-e ona cleaning surface 109. The cleaning surface 109 is a bottom surface ofthe cleaning pad 100 that is in contact with the floor surface 10. Theone or more sections 109 a-e on the cleaning surface 109 have a coveredratio between the meltblown abrasive fibers 107 and the wrap layer 105greater than 50%. The meltblown layer provides the pad with theadvantages of breaking surface tension that might otherwise cause thewet wrap layer to stick to a wet floor. By adding texture and topographyto a floor facing surface of the pad, the meltblown layer prevents thepad from sticking or encountering high drag forces. The meltblown layeralso provides the pad with surface texture for roughing up dirt anddebris stuck or dried to a floor surface and loosening dirt and debrisfor absorption by the airlaid inner core of the pad.

As shown in FIG. 3, the meltblown process 300 is a process that extrudesand draws molten polymer resins with a heated, high velocity air 310 toform fibers or filaments 107. The fibers/filaments 107 are cooled andare then formed into a web 106 on top of a moving screen 320. Thisprocess 300 is similar to spunbond, but the fibers 107 generated hereare much finer and range in the 0.1 to 20 μm (e.g., 0.1-5 μm) diameterrange. Meltblowing is also considered a spunmelt or spunlaid process.The process shown in FIG. 3 shows an extrusion die 312 (beam) thatextrudes the melt blown polypropylene fibers into a continuous porousconveyor to form the nonwoven web 106. It is made up of six majorcomponents: the extruder, metering pump, extrusion die, web forming, webconsolidation and winding. Other processes are possible as well.

There are two basic die designs 312 used with the meltblown technology,the single row die and the multi-row die. The key difference betweenthese two designs is the amount of air that is used as well as thethroughput of the die. With the multi-row die, much greater throughputmay be achieved. Multi-row dies usually have two to eighteen rows ofholes and approximately three hundred holes per inch, while theconventional single row dies have twenty-five to thirty-five holes perinch. Either die design 312 may be used to form the meltblown fibers107. Throughput for this process is much less than the 200+ kg/hr/meter(kilograms per hour per meter) obtained for spunbond or spunlace withits much larger fiber diameters. Conventional dies basically can extrude70 to 90 kg/hr/meter, while the multi-row die can achieve about 160kg/hr/meter.

In some implementations, the meltblown fibers 107 have a diameter ofbetween about 0.1 μm and about 5 μm with a mean of about 2.5 μm.Throughput and air flows have the greatest impact at reducing the fiberdiameter, with melt and air temperatures and distance of the die fromthe forming table have less of an impact. Optimizing the processvariables and using metallocene polypropylene may yield meltblown webswith mean fiber diameters in the range of 0.3 to 0.5 μm with maximumfiber diameters of less than 3 μm. A wrap layer 104 with meltblownfibers 107 of this size can provide a barrier against fluid leakage fromthe cleaning pad 100 by providing very high hydrohead webs withexcellent breathability. The meltblown fibers 107 may be created usinghomopolymer polypropylene; however, several other resins can be extrudedby the meltblown process as well, such as polyethylene, polyester,polyamides and polyvinyl alcohols. In some implementations, themeltblown layer 106 is formed from polylactic acids (PLA), abiodegradable nonwoven.

In some examples, the airlaid layers 101, 102, 103, the abrasion layer104 and the wrap layer 104 (i.e., the cleaning pad 100) have a combinedwidth W_(T) of between about 68 millimeters and about 80 millimeters anda combined length (not shown) of between about 200 millimeters and about212 millimeters. In some examples, the cleaning pad 100 including theairlaid layers 101, 102, 103, the abrasion layer 104 and the wrap layer105 have a combined thickness T_(T) of between 6.5 millimeters and about8.5 millimeters. Additionally, or alternatively, the airlaid layers 101,102, 103 have a combined airlaid width (W_(A1)+W_(A2)+W_(A3)) of between69 millimeters and about 75 millimeters and a combined airlaid length(L_(A1)+L_(A2)+L_(A3)) of between about 165 millimeters and about 171millimeters. The cleaning pad 100 withstands pressure being applied toit by an implement 400, 500 (e.g., robot or mop), since an implement400, 500 will cause back and forth movement of the cleaning pad 100mimicking a scrubbing action as the robot 400 traverses the floorsurface 10.

In some implementations, as the cleaning pad 100 is cleaning a floorsurface 10, it absorbs cleaning fluids 172 applied to the floor surface10. The cleaning pad 100 may absorb enough fluid without changing itsshape. Therefore, where the cleaning pad 100 is used along with acleaning robot 400, the cleaning pad 100 has substantially similardimensions before cleaning the floor surface 10 and after cleaning thefloor surface 10. The cleaning pad 100 may increase in volume when itabsorbs fluids. In some examples, the thickness of the cleaning padT_(T) increases by less than 30% after fluid absorption.

In some implementations, the wrap layer 104 has the specificationslisted in Table 1 below:

TABLE 1 Average Characteristic Unit Value Tolerance Test Method WrapLayer Weight g/m² 55 +/−10% ASTM D3776M- 09A Thickness mm 0.6 0.55-0.65WSP 120.6 Tensile N/2.54 cm 50 >40 ASTM D5034-09 Strength (MD) (DRY)N/2.54 cm 25 >20 (CD) Elongation at % (MD) 45 25-65 ASTM D5034-09 break(DRY) % (CD) 90  65-115 Water % 600 >500  WSP 10.0 (05) absorptionAbrasion Visual at OK No visible — resistance 80 cycles degradationMeltblown Abrasive Covered % 50 44-57 — surface ratio Scrubbing fiber μmN/A  8 μm-20 μm — average size

ASTM D3776M-09A and ASTM D5034-09 are standardized tests from theAmerican Society for Testing and Materials (ASTM). ASTM D3776M-09Acovers the measurement of fabric mass per unit area (weight) and isapplicable to most fabrics. ASTM D5034-09, also known as the Grab test,is a standard test method for breaking strength and elongation oftextile fabrics. WSP 120.6 and WSP 10.0 (05) are standardized testscreated by World Strategic Partners for testing the properties ofnonwoven fabrics.

Referring to FIGS. 1A-1D, 3, 4-6 and 9A-9C, the cleaning pad 100 isconfigured to scrub a floor surface 10 and absorb fluids on the floorsurface 10. In some examples, the cleaning pad 100 is attached to acleaning implement such as a mobile robot 400 or a handheld mop 500. Thecleaning implement 400, 500 may include a sprayer 462, 512 that sprays acleaning fluid 172 on the floor surface 10. The implement 400, 500 isused to scrub and remove any smears (e.g., dirt, oil, food, sauces,coffee, coffee grounds) that are being absorbed by the pad 100 alongwith the applied fluid 172 that dissolves and/or loosens the smears 22.Some of the smears may have viscoelastic properties, which exhibit bothviscous and elastic characteristic (e.g., honey). The cleaning pad 100is absorbent and has an outer surface 105 a that includes a randomlyapplied abrasive layer 106 comprising meltblown fibers 107. As theimplement 400, 500 moves about the floor surface 10, the cleaning pad100 wipes the floor surface 10 with the abrasive side 105 b containingthe abrasive layer 106 b of meltblown fibers and absorbs cleaningsolution sprayed onto the floor surface 10 with only a light amount offorce than otherwise required by scrubbing mops having a non-abrasivecleaning element.

Referring to FIG. 4, in some implementations, the implement 400 is acompact, lightweight autonomous mobile robot 400 that weighs less than 5lbs and navigates and cleans a floor surface 10. The mobile robot 400may include a body 410 supported by a drive system (not shown) that canmaneuver the robot 400 across the floor surface 10 based on a drivecommand having x, y, and θ components, for example. As shown, the robotbody 410 has a square shape. However, the body 410 may have othershapes, including but not limited to a circular shape, an oval shape, atear drop shape, a rectangular shape, a combination of a square orrectangular front and a circular back, or a longitudinally asymmetricalcombination of any of these shapes. The robot body 410 has a forwardportion 412 and a rearward portion 414. The body 410 also includes abottom portion (not shown) and a top portion 418. The bottom portion ofthe robot body 410 further comprises one or more rear cliff sensors (notshown) in one or both of the two rear corners of the robot 400 and oneor more forward cliff sensors located in one or both of the frontcorners of the mobile robot 400 for preventing falls from ledgedsurfaces. In embodiments, the cliff sensors may be mechanical dropsensors or light based proximity sensors, such as an IR (infrared) pair,a dual emitter, single receiver or dual receiver, single emitter IRlight based proximity sensor aimed downward at a floor surface 10. Insome examples, the one or more forward cliff sensors and one or morerear cliff sensors are placed at an angle relative to the forward andrear corners, respectively, such that they cut the corners, spanningbetween sidewalls of the robot 400 and covering the corner as closely aspossible to detect flooring height changes beyond a thresholdaccommodated by reversible robot wheel drop prior. Placing the cliffsensors proximate the corners of the robot 400 ensures that they willtrigger immediately when the robot 400 overhangs a flooring drop andprevent the robot wheels from advancing over the drop edge.

In some implementations, the forward portion 412 of the body 410 carriesa movable bumper 430 for detecting collisions in longitudinal (A,F) orlateral (L,R) directions. The bumper 430 has a shape complementing therobot body 410 and extends forward the robot body 410 making the overalldimension of the forward portion 412 wider than the rearward portion 414of the robot body 410 (the robot as shown has a square shape). Thebottom portion of the robot body 410 supports the cleaning pad 100. Inembodiments, the pad 100 extends beyond the width of the bumper 430 suchthat the robot 400 can position an outer edge of the pad 100 up to andalong a tough to reach surface or into a crevice, such a wall floorinterface, and such that the surface or crevice is cleaned by theextended edge of the pad 100 the while the robot 400 moves in a wallfollowing motion. The embodiment of a pad 100 extending beyond the widthof the bumper 430 enables the robot 400 to clean in cracks and crevicesbeyond the reach of the robot body 410. In embodiments, such as thoseshown in FIGS. 1A-1D and FIGS. 8A-8C and 9E, the pad 100 has bluntly cutends 100 d such that the airlaid layers 101, 102, 103 are exposed atboth ends 100 d of the pad 100. Instead of the wrap layer 105 beingsealed at the ends 100 d of the pad 100 and compressing the ends 100 dof the airlaid layers 101, 102, 103, the full length of the pad 100 isavailable for fluid absorption and cleaning. No portion of the airlaidcore is compressed by the wrap layer 105 and therefore unable to absorbfluid 172. Additionally, a used disposable pad 100 of this embodimentwill not have soaking wet, floppy ends of sealed wrap layer 105 at thecompletion of a cleaning run. All fluid 172 will be securely absorbedand held by the airlaid core, preventing any drips and preventing a userfrom undesirably contacting dirty wet ends of the pad 100.

As shown in FIGS. 4 and 9A-9G, the robot 400 may drive back and forth tocover a specific portion of the floor surface 10. As the robot 400drives back and forth, it cleans the area it is traversing and thereforeprovides a deep scrub to the floor surface 10. A reservoir 475 housed bythe robot body 410 holds a cleaning fluid 172 (i.e. cleaning solution)and may hold 170-230 mL of fluid. In embodiments, the reservoir 475holds 200 mL of fluid. The robot 400 may include a fluid applicator 462connected to the reservoir 475 by a tube. The fluid applicator 462 maybe a sprayer having at least one nozzle 464 that distributes fluid overthe floor surface 10. The fluid applicator 462 may have multiple nozzles464 each configured to spray the fluid at an angle and distancedifferent than another nozzle 464. In some examples, the robot 400includes two nozzles 464, vertically stacked in a recess in the fluidapplicator 462 and angled and spaced such that one nozzle 464 a spraysrelatively longer lengths of fluid 172 a forward and downward to coveran area in front of the robot 400 with a forward supply of applied fluid173 a and the other nozzle 464 b sprays relatively shorter lengths fluid172 b forward and downward to leave a rearward supply of applied fluid173 b on an area in front of but closer to the robot 400 than the areaof applied fluid 173 a dispensed by the top nozzle 464 a. Inembodiments, the nozzle 464 or nozzles 464 a, 464 b dispense fluid 172,172 a, 172 b in an area pattern that extends one robot width W_(R) andat least one robot length L_(R) in dimension. In some embodiments, thetop nozzle 464 a and bottom nozzle 464 b apply fluid 172 a, 172 b in twodistinct spaced apart strips of applied fluid 173 a, 173 b that do notextend to the full width W_(R) of the robot 400 such that the pad 100passes through the outer edges of the strips of applied fluid 173 a, 173b in forward and backward angled scrubbing motions as described herein.In embodiments, the strips of applied fluid 173 a, 173 b cover a widthW_(S) of 75-95% of the robot width W_(R) and a combined length L_(S) of75-95% of the robot length L_(R). In some implementations, the robot 400only sprays on traversed areas of the floor surface 10.

Moreover, the back and forth movement of the robot 400 breaks downstains on the surface floor 10. The broken down stains are then absorbedby the cleaning pad 100. In some examples, the cleaning pad 100 picks upenough of the sprayed fluid to avoid uneven streaks if the cleaning pad100 picks up too much liquid, e.g. fluid 172. In case of too littlefluid absorption, the robot 400 might leave fluid and wheel traces. Insome embodiments, the cleaning pad 100 leaves a residue of the fluid,which could be water or some other cleaning agent including solutionscontaining cleansing agents, to provide a visible sheen on the surfacefloor 10 being scrubbed. In some examples, the fluid containsantibacterial solution, e.g., an alcohol containing solution. A thinlayer of residue, therefore, is purposely not absorbed by the cleaningpad 100 to allow the fluid to kill a higher percentage of germs.Therefore, the cleaning pad 100 does not swell or expand and provides aminimal increase in total pad thickness T_(T). This characteristic ofthe cleaning pad 100 prevents the robot 400 from tilting backwards orpitching up if the cleaning pad 100 expands. The cleaning pad 100 issufficiently rigid to support the front of the robot. In some examples,the cleaning pad 100 absorbs up to 180 ml or 90% of the total fluidcontained in the robot reservoir 475. In some examples, the cleaning padholds about 55 to about 60 ml of fluid and a fully saturated wrap layerholds about 6 to about 8 ml of fluid 172. In some examples the ratio offluid retention in the airlaid core 101,102,103 to the outer wrap layer105 is about 9:1 to about 5:1.

The pad 100 and robot 400 are sized and shaped such that the transfer offluid from the reservoir to the absorptive pad 100 maintains the forwardand aft balance of the less than 5 lb robot 400 during dynamic motion.The fluid distribution is designed so that the robot 400 continuallypropels the pad 100 over a floor surface 10 without the interference ofthe increasingly saturated pad 100 and decreasingly occupied fluidreservoir 475 lifting the back 414 of the robot 400 and pitching thefront 412 of the robot 400 downward and thereby applyingmovement-prohibitive downward force to the robot 400. The robot 400 isable to move the pad 100 across the floor surface 10 even when the pad100 is fully saturated with fluid. The robot 400 however includes thefeature of tracking the amount of floor surface 10 travelled and/or theamount of fluid remaining in the reservoir 475 and provides an audibleand/or visible alert to a user that the pad 100 requires replacementand/or the reservoir 475 requires refilling. In embodiments, the robot400 stops moving and remains in place on the floor surface if the pad100 is fully saturated, and there remains floor to be cleaned once thepad 100 is replaced.

FIGS. 9A through 9G detail the spraying, pad wetting, and scrubbingmotions of one embodiment of the mobile robot 400. In someimplementations, the robot 400 only applies fluid 172 to areas of thefloor surface 10 that the robot 100 has already traversed. In oneexample, the fluid applicator 462 has multiple nozzles 464 a, 464 b eachconfigured to spray the fluid 172 a, 172 b in a direction different thananother nozzle 464 a, 164 b. The fluid applicator 462 may apply fluid172 downward rather than outward, dripping or spraying fluid 172directly in front of the robot 100. In some examples, the fluidapplicator 462 is a microfiber cloth or strip, a fluid dispersion brush,or a sprayer.

Referring to FIGS. 9A-9D and 9F-9G, in some implementations, the robot400 may execute a cleaning behavior by moving in a forward direction Ftoward an obstacle 20, followed by moving in a backward or reversedirection A. As indicated in FIGS. 9A and 9B, the robot 400 may drive ina forward drive direction a first distance Fd to a first location L1. Asthe robot 400 moves backwards a second distance Ad to a second locationL2, the nozzles 464 a, 464 b simultaneously spray longer lengths fluid172 a and shorter lengths of fluid 172 b onto the floor surface 10 in aforward and/or downward direction in front of the robot 400 after therobot 400 has moved at least a distance D across an area of the floorsurface 10 that was already traversed in the forward drive direction F.In one example, the fluid 172 is applied to an area substantially equalto or less than the area footprint AF of the robot 400. Because distanceD is the distance spanning at least the length L_(R) of the robot 400,the robot 400 determines that the area of floor 10 traverses is clearfloor surface 10 unoccupied by furniture, walls 20, cliffs, carpets orother surfaces or obstacles onto which cleaning fluid 172 would beapplied if the robot 100 had not already verified the presence of aclear floor surface 10 for receiving cleaning fluid 172. By moving in aforward direction F and then backing up prior to applying cleaning fluid172, the robot 400 identifies boundaries, such as a flooring changes andwalls, and prevents fluid damage to those items.

As shown in FIGS. 4, 9B and 9C, in some examples, the fluid applicator462 is a sprayer 462 that includes at least two nozzles 464 a, 464 b,each distributing the fluid 172 evenly across the floor surface 10 intwo strips of applied fluid 173 a, 173 b. The two nozzles 464 a, 464 bare each configured to spray the fluid at an angle and distancedifferent than another nozzle 464 a, 464 b. In some examples, the twonozzles 464 a, 464 b are vertically stacked in a recess in the fluidapplicator 462 and angled from horizontal and spaced apart from oneanother such that one nozzle 464 a sprays relatively longer lengths offluid 172 a forward and downward to cover an area in front of the robot400 with a forward supply of applied fluid 173 a, and the other nozzle464 b sprays relatively shorter lengths fluid 172 b forward and downwardto leave a rearward supply of applied fluid 173 b on an area in front ofbut closer to the robot 400 than the area of applied fluid 173 adispensed by the top nozzle 464 a. In embodiments, the nozzle 464 ornozzles 464 a, 464 b dispense fluid 172, 172 a, 172 b in an area patternthat extends one robot width W_(R) and at least one robot length L_(R)in dimension. In some embodiments, the top nozzle 464 a and bottomnozzle 464 b apply fluid 172 a, 172 b in two distinct spaced apartstrips of applied fluid 173 a, 173 b that do not extend to the fullwidth W_(R) of the robot 400 such that the pad 100 passes through theouter edges of the strips of applied fluid 173 a, 173 b in forward andbackward angled scrubbing motions as described herein. In embodiments,the strips of applied fluid 173 a, 173 b cover a width W_(S) of 75-95%of the robot width W_(R) and a combined length L_(S) of 75-95% of therobot length L_(R). In embodiments, the strips of applied fluid 173 a,173 b may be substantially rectangular shaped or ellipse shaped. Inembodiments, the nozzles 464 a, 464 b complete each spray cycle bysucking in a small volume of fluid at the opening of the nozzle so thatno fluid 172 leaks from the nozzle following each instance of spraying.

Referring to FIGS. 9D, 9F and 9G, in some examples, the robot 400 maydrive back and forth to cover a specific portion of the floor surface10, wetting the cleaning pad 100 at the start of a cleaning run and/orscrubbing the floor surface 10. The robot 400 drives back and forth,cleaning the area traverse and therefore providing a thorough scrub tothe floor surface 10. The robot 400 oscillates the attached pad 100 inan orbit of 12-15 mm to scrub the floor 10 and applies 1 pound ofdownward pushing force or less to the pad.

In some examples, the fluid applicator 462 applies fluid 172 to an areain front of the cleaning pad 100 and in the direction of travel (e.g.,forward direction F) of the mobile robot 100. In some examples, thefluid 172 is applied to an area the cleaning pad 100 has previouslyoccupied. In some examples, the area the cleaning pad 100 has occupiedis recorded on a stored map that is accessible to a robot controller150, as shown in the diagram of FIG. 10. The robot 400 may include acleaning system 1060 for cleaning or treating a floor surface 10.

In some examples, the robot 400 knows where it has been based on storingits coverage locations on a map stored on the non-transitory-memory 1054of the robot 400 or on an external storage medium accessible by therobot 400 through wired or wireless means during a cleaning run. Therobot 400 sensors 5010 may include a camera and/or one or more ranginglasers for building a map of a space. In some examples, the robotcontroller 1050 uses the map of walls, furniture, flooring changes andother obstacles 10 to position and pose the robot 400 at locations farenough away from obstacles and/or flooring changes prior to theapplication of cleaning fluid 172. This has the advantage of applyingfluid 172 to areas of floor surface 10 having no known obstaclesthereon.

In some examples, the robot 100 moves in a back and forth motion tomoisten the cleaning pad 100 and/or scrub the floor surface 10 to whichfluid 172 has been applied. The robot 400 may move in a birdsfootpattern through the footprint area AF on the floor surface 10 to whichfluid 172 has been applied. As depicted, in some implementations, thebirdsfoot cleaning routine involves moving the robot 100 in forwarddirection F and a backward or reverse direction A along a centertrajectory 1000 and in forward direction F and a backward direction Aalong left 1010 and right 1005 trajectories. In some examples, the lefttrajectory 1010 and the right trajectory 1005 are arcuate trajectoriesthat extend outward in an arc from a starting point along the centertrajectory 1000. The left trajectory 1010 and the right trajectory 1005may be straight line trajectories that extend outward in a straight linefrom the center trajectory 1000.

FIGS. 9D and 9F depict two birdsfoot trajectories. In the example ofFIG. 9D, the robot 400 moves in a forward direction F from Position Aalong the center trajectory 1000 until it encounters a wall 20 andtriggers a sensor 5010, such as a bump sensor, at Position B. The robot400 then moves in a backward direction A along the center trajectory toa distance equal to or greater than the distance to be covered by fluidapplication. For example, the robot 400 moves backward along the centertrajectory 1000 by at least one robot length 1 to Position G, which maybe the same position as Position A. The robot 400 applies fluid 172 toan area substantially equal to or less than the footprint area AF of therobot 100 and returns to the wall 20, the cleaning pad 400 passingthrough the fluid 172 and cleaning the floor surface 10. From positionB, the robot 100 retracts either along a left trajectory 1010 or a righttrajectory 1005 before returning to Position B and covering theremaining trajectory. Each time the robot 400 moves forward and backwardalong the center trajectory 1000, left trajectory 1010 and righttrajectory 1005, the cleaning pad 100 passes through the applied fluid172, scrubbing dirt, debris and other particulate matter from the floorsurface 10 to which the fluid 172 is applied and absorbing the dirtyfluid into the cleaning pad 100 and away from the floor surface 10. Thescrubbing motion of the moistened pad combined with the solventcharacteristics of the cleaning fluid 172 breaks down and loosens driedstains and dirt. The cleaning fluid 172 applied by the robot 400suspends loosened debris such that the cleaning pad 100 absorbs thesuspended debris and wicks it away from the floor surface 10.

In the example of FIG. 9F, the robot 400 similarly moves from a startingposition, Position A, through applied fluid 172, along a centertrajectory 1000 to a wall position, Position B. The robot 400 backs offof the wall 20 along the center trajectory 1000 to Position C, which maybe the same position as Position A, before covering left and righttrajectories 1010, 1005, extending to positions D and F, with thecleaning fluid 172 distributed along the trajectories 1010, 1005 by thecleaning pad 100. In one example, each time the robot 400 extends alonga trajectory outward from the center trajectory 1000, the robot 400returns to a position along the center trajectory as indicated byPositions A, C, E and G, as depicted in FIG. 9F. In someimplementations, the robot 400 may vary the sequence of backwarddirection A movements and forward direction F movements along one ormore distinct trajectories to move the cleaning pad 100 and cleaningfluid 172 in an effective and efficient coverage pattern across thefloor surface.

In some examples, the robot 100 may move in a birdsfoot coverage patternto moisten all portions of the cleaning pad 100 upon starting a cleaningrun. As depicted in FIG. 9E, the bottom surface 100 b of the cleaningpad 100 has a center area PC and right and left lateral edge areas PRand PL. When the robot 100 starts a cleaning run, or cleaning routine,the cleaning pad 100 is dry and needs to be moistened to reduce frictionand also to spread cleaning fluid 172 along the floor surface 10 toscrub debris therefrom.

The robot 400 therefore applies fluid at a higher volumetric flow rateinitially at the start of a cleaning run such that the cleaning pad 100is readily moistened. In one implementation, the first volumetric flowrate is set by spraying about 1 mL of fluid every 1.5 feet initially fora period of time such as 1-3 minutes, and the second volumetric flowrate is set by spraying every 3 feet, wherein each spray of fluid isless than 1 mL of volume. In embodiments, the robot 400 applies fluid172 every one to two feet at the start of a run to saturate the wraplayer 105 of the pad 100 early in the cleaning run. After a period oftime and/or distance, such as a duration of 2-10 minutes, the robot 400applies fluid at intervals of every three to five feet because the pad100 is moistened and able to scrub the floor 10. As FIG. 9G depicts, insome examples, at the start of a cleaning run, the robot 400 drives thecleaning pad 100 through applied fluid 172 such that the center area PCof the bottom surface 100 b of the cleaning pad 100 and the left andright lateral edge areas PR and PL of the cleaning pad 100 each passthrough the applied fluid 172 separately, thereby moistening the entirecleaning pad 100 along the entire bottom surface 100 b of the cleaningpad 100 in contact with the floor surface 10.

In the example of FIG. 9G, the robot 400 moves in a forward direction Fand 10 then backward direction A along a center trajectory 1000, passingthe center of the pad 100 through the applied fluid 172. The robot 400then drives in a forward direction F and backward direction A along aright trajectory 1005, passing the left lateral area PL of the cleaningpad 100 through the applied fluid 172. The robot 100 then drives in aforward direction F and backward direction A along a left trajectory1010, passing the right lateral area PR of the cleaning pad 100 throughthe applied fluid 172. At the start of the cleaning run, the robotapplies fluid 172 at a relatively high initial volumetric flow rate Viand/or high initial frequency of application, applying a larger quantityof fluid 172 more frequently to the surface 10 and/or applying a fixedamount of fluid 172 more frequently to the surface 10 to moisten thecleaning pad 100 quickly. Moistening the cleaning pad reduces frictionand also enables the pad 100 to dissolve more debris 22 withoutrequiring more frequent applications of fluid 172. In embodiments, thecoefficient of friction of the warp layer 105 of the pad 100 varies from0.3 to 0.5 depending on material of the floor 10 and wetness of the pad100. In one embodiment, a dry pad 100 moving on glass has a coefficientof friction of around 0.4 to 0.5, and wet on tiles has a coefficient offriction of about 0.25 to 0.4.

Once the wrap layer 105 of the cleaning pad 100 is moistened, the robot400 continues its cleaning run and subsequently applies fluid 172 at asecond volumetric flow rate Vf. This second volumetric flow rate Vf isrelatively lower than the initial flow rate Vi at the start of thecleaning run because the cleaning pad 100 is already moistened andeffectively moves cleaning fluid across the surface 10 as it scrubs. Inone implementation, the initial volumetric flow rate Vi is set byspraying about 1 mL of fluid every 1.5 feet initially for a period oftime such as 1-3 minutes, and the second volumetric flow rate Vf is setby spraying every 3 feet, wherein each spray of fluid is less than 1 mLof volume. The robot 400 adjusts the volumetric flow rate V such that acleaning pad 100 of specified dimensions is moistened on the bottomsurface 100 b (FIG. 9E) without being fully wetted to capacityinternally in the airlaid layers 101, 102, 103. The bottom surface 100 bof the cleaning pad 100 is initially moistened without the absorbentinterior of the pad 100 being water logged such that the cleaning pad100 remains fully absorbent for the remainder of the cleaning run. Theback and forth movement of the robot 400 breaks down stains 22 on thefloor surface 10. The broken down stains 22 are then absorbed by thecleaning pad 100.

In some examples, the cleaning pad 100 picks up enough of the sprayedfluid 172 to avoid uneven streaks. In some examples, the cleaning pad100 leaves a residue of the solution to provide a visible sheen to thefloor surface 10 being scrubbed. In some examples, the fluid 172contains antibacterial solution; therefore, a thin layer of residue ispurposely not absorbed by the cleaning pad 100 to allow the fluid 172 tokill a higher percentage of germs.

In an embodiment, the pad may be scented. The scent agent may beintegrated into or applied onto one or more of the airlaid core layers,the liner or a combination of the airlaid layers and liner. The scentingagent may be inert in a pre-activation stage and activated by fluid torelease scent so that the pad only produces a scent during use andotherwise produces no scent while stored. In another embodiment, the padincludes a cleaning agent or surfactant that may be integrated into orapplied onto one or more of the airlaid core layers, the liner, or acombination of the airlaid layers and liner. In one embodiment, thecleaning agent is applied to only the back surface (unexposed,non-meltblown side) of the liner in contact with the lower most airlaidcore member such that the cleaning agent is released through the porousliner, onto the cleaning surface when in contact with fluid. Thecleaning agent may be a foaming agent and/or a cleaning agent with avisibly glossy sheen indicating the application of the cleaning agentthe cleaning surface. In another embodiment, the pad includes one ormore chemical preservatives applied to or manufactured within thecardboard backing element. The preservatives are selected to prevent thegrowth of wood spores that may be present in the wood based backingelement. Some embodiments of the pad may include all of thesefeatures—conventional scent agent, cleaning agent, antibacterial agentand preservatives—or combinations of fewer than all of these features,including, for example, an encapsulated scent.

Referring to FIG. 5, in some examples, the implement 500 is a mop 500.The mop 500 includes a body 502 supporting a reservoir 504 that holds acleaning fluid 172 (e.g. a cleaning solution). A handle 506 is disposedon one side of the body 502. The handle includes a controller 508 forcontrolling the release of the fluid from the reservoir 504. A movablerotatable base 510 is disposed on the other end of the body 502 oppositethe handle 506. The base 510 includes a fluid applicator 512 connectedto the reservoir 504 by a tube (not shown). The fluid applicator 512 maybe a sprayer having at least one nozzle 514 that distributes fluid overthe floor surface 10. The nozzle 514 sprays forward and downwards of thebase 510 towards the floor surface 10. A user controlling the controller508 sprays the fluid 172 when needed. The fluid applicator 512 may havemultiple nozzles 514 each configured to spray the fluid in a directiondifferent than another nozzle 514.

Referring to FIGS. 6, and 8E-8G, a retainer 600, 600 a, 600 b may bedisposed on the implement 400, 500 supporting the cleaning pad 100. Theretainer 600, 600 a, 600 b is disposed on a bottom portion of theimplement 400, 500 for retaining the cleaning pad 100. In oneembodiment, the retainer 600 may include hook-and-loop fasteners, and inanother embodiment, the retainer 600 may include clips, or retentionbrackets, and selectively moveable clips or retention brackets forselectively releasing the pad for removal. Other types of retainers maybe used to connect the cleaning pad 100 to implement 400, 500, such assnaps, clamps, brackets, adhesive, etc., which may be configured toallow the release of the cleaning pad 100 upon activation of a padrelease mechanism located on the implement 400, 500 such that user neednot touch the dirty used pad to remove the pad from the cleaningimplement 400, 500.

FIG. 7 provides an exemplary arrangement of operations for a method 700of constructing a cleaning pad 100. The method 700 includes disposing710 a first airlaid layer 101 on a second airlaid layer 102 anddisposing 720 the second airlaid layer 102 on a third airlaid layer 103.The method 700 further includes wrapping 730 a wrap layer 104 around thefirst, second, and third airlaid layers 101, 102, 103. The wrap layer104 includes a spunlace wrap layer 105, and a meltblown abrasive 107adhered to the spunlace wrap layer 105.

In some examples, the method 700 further includes adhering and randomlyarranging meltblown abrasive 107 on the spunlace wrap layer 105.Additionally or alternatively, the meltblown abrasive fibers may have adiameter of between about 0.1 μm and about 20 μm. The method 700 mayfurther include arranging the meltblown abrasive and the spunlace wraplayer 105 to have a collective thickness of between 0.5 mm and about 0.7mm on the spunlace wrap layer 105. In some examples, the meltblownabrasive 107 creates a thickness gap of 0.5 mm between the wrap layer105 and the floor 10. Because of this thickness gap, the pad 100 canpick up a 1.5 mm diameter bubble of fluid sitting on the floor 10 withsurface tension without requiring force. The lowest points of theembossed cover 105 layer are only 0.5 mm from the floor 10 and theremainder of the surface area of wrap layer 105 is 3 mm from the floor10.

The method 700 may further include arranging the meltblown abrasive 107on the spunlace wrap layer 105 to provide a covered surface ratiobetween the meltblown abrasive 107 and the spunlace wrap layer 105 ofbetween about 60% and about 70%. In some examples, the method 700 mayinclude adhering the first airlaid layer 101 to the second airlaid layer102 and adhering the second airlaid layer 102 to the third airlaid layer103. The airlaid layers 101, 102, 103 may be of a cellulose basedtextile material (e.g., a material including fluff pulp).

In some implementations, the method 700 may include where the first,second, and third airlaid layers 101, 102, 103, the spunlace wrap layer105, and the meltblown abrasive are configured to increase in thicknessby less than 30% after fluid absorption. The method 700 may furtherinclude embossing the spunlace layer 105. The method 700 may alsoinclude disposing sodium polyacrylate in one or more of the airlaidlayers 101, 102, 103.

In some examples, the method 700 further includes configuring theairlaid layers 101, 102, 103 and wrap layer 104 to have a combined widthof between about 80 millimeters and about 68 millimeters, and a combinedlength of between about 200 millimeters and about 212 millimeters. Themethod 700 may further include configuring the airlaid layers 101, 102,103 and the wrap layer 104 to have a combined thickness of between about6.5 millimeters and about 8.5 millimeters. The method 700 may includeconfiguring the airlaid layers 101, 102, 103 to have a combined airlaidwidth of between 69 millimeters and about 75 millimeters, and a combinedairlaid length of between about 165 millimeters and about 171millimeters.

FIGS. 8E-G demonstrate an exemplary release mechanism for the pad 100 asdescribed herein. FIGS. 8A-8C show an embodiment of the pad 100 having acore of three airlaid layers 101, 102, 103 bonded and enclosed in a wraplayer 105 adhered to the top surface of the top airlaid layer 101.Additionally, the embodiment of FIGS. 8A-8C include a cardboard backinglayer 85 adhered to the top surface of the pad 100. The cardboardbacking layer 85 protrudes beyond the longitudinal edges of the pad 100and the protruding longitudinal edges 86 of the cardboard backing layer85 attach to the pad holder 82 of the robot 100. In one embodiment, thecardboard backing layer 85 is between 0.02″ and 0.03″ thick, between 68and 72 mm wide and between 90-94 mm long. In one embodiment, thecardboard backing layer 85 is 0.026″ thick, 70 mm wide and 92 mm long.In one embodiment, the cardboard backing layer 85 is coated on bothsides with a water resistant coating, such as wax or polymer or acombination of water resistant materials, such as wax/polyvinyl alcohol,polyamine, and the cardboard backing layer 85 does not disintegrate whenwetted.

In embodiments, the bottom surface 100 b of the pad 100 may include oneor more hair catching strips 100 c for catch and collect loose hairduring cleaning. In the embodiment of FIG. 9E, two hair catching strips100 c are depicted in dashed line to indicate the option nature of thisfeature. In an embodiment having one or more hair catching strips 100 c,the strip or strips 100 c may be located on outer longitudinal edges ofthe pad 100 or in a single strip on either longitudinal edge of the pador down the middle of the pad. In embodiments, each hair catching strip100 c is less than 30% of the total surface area of the bottom surface100 b of the pad 100 and preferably is less than 20% of the surface areaof the bottom surface 100 b of the pad 100. The hair catching strip 100c may be a strip of material added to the wrap layer 105 that includesloose fibers with catching features, such as Velcro® hooks, rough edgedfibers or fibers with a fused tip.

As shown in FIGS. 8E and 8G, the pad 100 as described herein can besecured to an autonomous robot through a pad holder 82 which can beattached to the robot 400. An exemplary pad release mechanism 83 is alsoshown in an up or pad-secure position. The pad release mechanism 83includes a retainer 600 a, or lip, that holds the pad 100 securely inplace by grasping the protruding longitudinal edges 86 of the cardboardbacking layer 85. In the version shown, the tip or end 84 of the padrelease mechanism 83 includes a moveable retention clip 600 a and aneject protrusion 84 that slides up through a slot or opening in the padholder 82 when the pad is inserted into the holder 82, and is pushedinto a down position to release the secured pad 100 as shown in FIG. 8G,as shown here pushing down on the attached backing layer 85, e.g.cardboard backing. The relationship between the pad and the pad holder82 is also shown in a top view in FIG. 8F. In one embodiment, the padrelease mechanism 83 is activated by a toggle button 477 located underthe handle 419 of the robot 400, as shown in FIG. 4. The toggle motionis indicated by the dotted double arrow 478. Toggling the toggle button477 moves a spring actuator that rotates the pad release mechanism 83,moving the retention clip 600 a away from the cardboard backing layer 85and moving the eject protrusion 84 through the slot in the pad holder882 so that the eject protrusion pushes the pad 100 out of the holder.

Returning to FIGS. 8A and 8B, in embodiments, the cardboard backinglayer 85 may include cutouts 88 centered along the protrudinglongitudinal edges 86 of the cardboard backing layer 85 andcorresponding in position with raised protrusion 94 on the bottom of thepad holder 82, as shown in FIG. 8D. In another embodiment, the cardboardbacking layer 85 contains a first set of cutouts 88 centered on theprotruding longitudinal edges 86 of the cardboard backing layer 85 and asecond set of cutouts 90 on the lateral edges of the cardboard backinglayer 85. The cutouts 88, 90 are symmetrically centered along thelongitudinal center axis PCA_(lon) of the pad 100 and lateral centeraxis PCA_(lat) of the pad 100 and engage with corresponding protrusions92, 94 centered on the longitudinal center axis HCA_(lon) of theunderside of the pad holder 82 and lateral center axis PCA_(lat) on theunderside of the pad holder 82. The pad holder 82 of the embodiment ofFIG. 8D includes three raised protrusions 92, 94. This is so that a usermay install the pad 100 in either of two identical directions (180degrees opposite to one another) while allowing the pad holder 82 tomore easily release the pad 100 when the release mechanism 83 istriggered. Other embodiments of the pad holder include four protrusions92, 94 corresponding in position to the four cutouts 88, 90 on thecardboard backing layer in FIG. 8C. In still other embodiments, the padholder 82 and pad 100 respectively include raised protrusions andcorresponding cut outs in any other number or configuration for holdingthe pad in place and enabling selective release.

In FIG. 8D, the raised protrusion 94 on the longitudinal edge of the padholder 82 is obscured by the retaining bracket 600 a, which is shown inphantom view so that the raised protrusion 94 therebeneath is visible inthe exemplary view. The protrusions 92, 94 both poke yoke attachment ofthe disposable pad 100 to the bottom of the pad holder 82 so thatalignment if the pad 100 to the holder 82 is precise and retain the pad100 relatively stationary to the pad holder 82 by preventing lateraland/or transverse slippage.

Because the cutouts 88, 90 extend into the surface area of the cardboardbacking layer 85, they respectively interface with more lateral andlongitudinal surface area of the raised protrusions 92, 94 and the padis held in place against rotational forces as well by thecutout-protrusion retention system. The robot 100 moves in a scrubbingmotion, as described above, and, in embodiments, the pad holder 82oscillates the pad for additional scrubbing. In embodiments, the robot400 oscillates the attached pad 100 in an orbit of 12-15 mm to scrub thefloor 10 and applies 1 pound of downward pushing force or less to thepad. By aligning cutouts 88, 90 in the cardboard backing layer 85 withprotrusions 92, 94, the pad 100 remains stationary relative to theholder during use, and the application of scrubbing motion, includingoscillation motion, directly transfers from the pad holder 82 throughthe layers of the pad without loss of transferred movement.

In embodiments, the pad of FIGS. 1A-1D and 8A-8C are disposable pads. Inother embodiments, the pad 100 is a reusable microfiber cloth pad havingthe same absorptive characteristics as those described herein withregard to embodiments. In embodiments having a washable, reusablemicrofiber cloth, the top surface of the cloth includes a secured stiffbacking layer shaped and positioned like the cardboard backing layer ofthe embodiments of FIGS. 8A-8C. The stiff backing layer is made of heatresistant, washable material that can be machine dried without meltingor degrading the backing. The stiff backing layer is dimensioned and hascutouts as described herein for interchangeable use with the embodimentof the pad holder 82 described with regard to the embodiments of FIGS.8A-8G.

In other examples, the pad 100 is intended for use as a disposable drycloth and comprises a single layer of needle punched spunbond orspunlace material having exposed fibers for entrapping hair. The dry pad100 embodiment further comprises a chemical treatment that adds atackiness characteristic to the pad 100 for retaining dirt and debris.In one embodiment, the chemical treatment is a material such as thatmarketed under the trade name DRAKESOL.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims. Forexample, the actions recited in the claims can be performed in adifferent order and still achieve desirable results.

What is claimed is:
 1. A mobile floor cleaning robot comprising: a robotbody defining a forward drive direction; a drive supporting the robotbody to maneuver the robot across a floor surface the drive comprisingright and left drive wheels disposed on corresponding right and leftportions of the robot body; and a cleaning assembly disposed on therobot body, the cleaning assembly comprising: a pad holder disposedforward of the drive wheels and having a top portion and a bottomportion, the bottom portion having a bottom surface to receive acleaning pad, the bottom surface of the pad holder comprising at least40% of a surface area of a footprint of the robot, and the bottomportion having raised protrusions extending therefrom; and an orbitaloscillator having less than 1 cm of orbital range disposed on the topportion of the pad holder; wherein the pad holder is configured topermit more than 80 percent of the orbital range of the orbitaloscillator to be transmitted from a top of the received cleaning pad toa bottom surface of the received cleaning pad and wherein the pad holderhas a release mechanism configured to eject the received cleaning padfrom the bottom surface of the pad holder upon actuation of the releasemechanism.
 2. The robot of claim 1, wherein the cleaning assemblyfurther comprises: a reservoir to hold a volume of fluid; and a fluidapplicator in fluid communication with the reservoir, the fluidapplicator configured to apply the fluid along the forward drivedirection and forward of the pad holder.
 3. The robot of claim 2,wherein the cleaning pad is configured to absorb about 90% of the volumeheld in the reservoir.
 4. The robot of claim 1, further comprising abacking layer on the cleaning pad for engaging with the pad holder. 5.The robot of claim 4, wherein at least one raised protrusion on thebottom portion of the pad holder is positioned for aligning to andengaging with a shaped slot cut out of the backing layer.
 6. The robotof claim 2, wherein the fluid applicator comprises at least two nozzlesto apply the fluid in two strips across the floor surface in the forwarddrive direction.
 7. The robot of claim 6, wherein the at least twonozzles are vertically stacked in a recess in the fluid applicator andangled relative to a horizontal plane to spray fluid forward anddownward.
 8. The robot of claim 7, wherein a first of the at least twonozzles is angled relative to the horizontal plane to spray fluid tocover a first area on the floor surface, a second of the at least twonozzles is angled relative to the horizontal plane to spray fluid tocover a second area of the floor surface, and the first of the at leasttwo nozzles and the second of the at least two nozzles are spaced apartfrom one another such that the first area is forward of the second area.9. The robot of claim 2, wherein the fluid applicator is configured toapply fluid in an area pattern on the floor surface, the area patternextending at least one robot width and extending at least one robotlength.
 10. The robot of claim 2, wherein the fluid applicator isconfigured to apply fluid in an area pattern on the floor surface, thearea pattern extending less than a robot width.
 11. The robot of claim4, wherein the backing layer is a stiff backing layer, and the padholder is configured to receive longitudinal edges of the stiff backinglayer that extend beyond longitudinal edges of the cleaning pad.
 12. Therobot of claim 11, wherein the release mechanism comprises a retainer tograsp a first of the longitudinal edges of the stiff backing layer, anda movable retention clip to grasp a second of the longitudinal edges ofthe stiff backing layer.
 13. The robot of claim 1, wherein an overallweight of the robot without retaining any fluid is between about 1 kgand about 1.5 kg and with retaining fluid is between about 1.5 kg to 4.5kg.
 14. The robot of claim 1, wherein the robot applies fluid to thefloor surface at an initial volumetric flow rate to moisten the cleaningpad, the initial volumetric flow rate being relatively higher than asubsequent volumetric flow rate when the cleaning pad is moistened. 15.The robot of claim 14, the initial volumetric flow rate is set byspraying 1 mL of fluid every 30 cm for a period of about 1 to 3 minutes,and the subsequent volumetric flow rate is set by spraying every 3 feet,wherein each spray of fluid is less than 1 mL of volume.
 16. The robotof claim 1, wherein the bottom surface of the pad holder is arrangedwithin between about ½ cm and about 1½ cm of the floor surface.
 17. Therobot of claim 1, wherein the drive is configured to maneuver the robotin a birdsfoot motion in which the robot moves forward and backwardalong a center trajectory, forward and backward along a leftwardtrajectory from a starting point along the center trajectory, andforward and backward along a rightward trajectory from a starting pointalong the center trajectory.
 18. The robot of claim 1, wherein the robotbody and the pad holder both define substantially rectangular footprints.
 19. The robot of claim 1, wherein the cleaning assembly furtherincludes a post disposed on the top portion of the pad holder, the postsized to receive a corresponding aperture defined by the robot.
 20. Therobot of claim 19, wherein the post has a cross-sectional diameter thatvaries along a length of the post.
 21. The robot of claim 19, whereinthe post includes a vibration dampening material.
 22. The robot of claim1, further comprising an arm pivotally attaching the drive wheels to therobot body to enable vertical movement of the drive wheels relative tothe floor surface.